Is there any easy technique written in Bhagavad GITA or any religious books to control lust/self-pleasure?
The quickest and easiest way is control of diet or aahahara as it is known in Sanskrit. There are two categories from Ayurveda - pathya and apathya. You need to stick to pathya foods. Pathya means restricted. By restriction I mean sattvic foods. One needs to completely avoid rajasic and tamasic foods. These are available by the dozen these days. From a modern contemporary Kali Yuga perspective these are the ubiquitous spicy masala foods and most definitely junk food. You need to figure out a diet which is nutritious and wholesome for you. By sattvic I mean do not starve yourself. A good Ayurvedic Vaidya would be helpful to guide you in this regard.
The BG offers a broad guideline on what the sattvic foods are - Sattvic foods Please remember that there is a deity in the stomach - Vaishvanara and this is mentioned in BG - Digesting different kinds of food. During youth and middle age the stomach is able to bear the junk foods we eat. As time passes onto old age the karmic reactions will start to appear.
So the key question is what are sattvic foods in today's environment? A modern self realized Jnani has described what sattvic foods are Ramana Maharishi diet recommendations-
Mrs. Piggott returned from Madras for a further visit. She asked questions relating to diet regulation.
D.: What diet is prescribed for a sadhak (one who is engaged in spiritual practices)?
M.: Satvic food in limited quantities.
D.: What is satvic food?
M.: Bread, fruits, vegetables, milk, etc.
D.: Some people take fish in North India. May it be done?
No answer was made by the Maharshi.
Care must also be given to how foods are prepared and the environment in which they are prepared. As I mention below a return to ancient traditional practices is what Sri Krishna is asking in BG and so usage of clay pots, cast iron skillet, kalchattis(cooking pot made with soapstone) and wooden ladle is strongly encouraged. If one goes to an Indian village today this is how traditional sattvic food is cooked and offered and then only consumed and following these practices will help the aspirant enormously.
A predominantly sattvic diet(with some rajasic spices) will have a definite impact on the dream state(which is where the lust/carnal pleasures get activated) i.e. during night. You need to also stop spending time in front of the computer and mobile phone beyond 7 pm i.e. eat early before 8 pm and avoid any internet and mobile after you eat. In ancient India there was no electricity as there is in modern homes. People used to light lamps and the house fire. So food was consumed after the evening sandhya and generally people used to sleep after their evening food or practise their sadhana.
Following the path of the ancients Modern Indian cities due to their highly populated areas are highly tamasic(noisy, dusty and congested) and so it would be beneficial to recreate the atmosphere of the ancients in our daily lives whenever time permits. Reconnecting with our roots in whatever possible (spending time in a village from time to time) or an ashrama that promotes an traditional lifestyle.
I am quoting some relevant slokas from the Gita :
3.37 The Blessed Lord said This lust, this anger, born of the quality of rajas, is a great devourer, a great sinner. Know this to be the enemy here.
3.40 The organs, mind, and the intellect are said to be its abode. This one diversely deludes the embodied being by veiling Knowledge with the help of these.
3.41 Therefore, O scion of the Bharata dynasty, after first controlling the organs, renounce this one, which is sinful and a destroyer of learning and wisdom.
3.42 They say that the organs are superior (to the gross body); the mind is superior to the organs; but the intellect is superior to the mind. However, the one who is superior to the intellect is He [the Self].
•3.43 Understanding the Self thus [Understanding ৷৷ .thus:that lust can be conered through the knowledge of the Self.] as superior to the intellect, and completely establishing (the Self) is spiritual absorption with the (help of) the mind, O mighty-armed one, vanish the enemy in the form of lust, which is difficult to subdue.
'AhAra-suddhau sattvasuddhih' is a very renowned saying. Pure sattvik food is a must in the beginning for all the spiritual aspirants.
Sri Ramakrishna is His Kathamrita recommends chanting of the NAma of God and changing the direction of the lust towards God as two ways to dominate lust.He also asks not be bothered much about the presence of lust in mind and focus on God. When one moves towards east, he automatically distances himself from west---said He. (Reference : Sri Sri Ramakrishna-Kathamrita and Sri Sri Ramakrishna-Lilaprasanga)
Sri Bhagavan also says the same in His Gita:
18.66 Abandoning all forms of rites and duties, take refuge in Me alone. I shall free you from all sins. (Therefore) do not grieve.