Cyber-crime complaint can be withdrawn only through court in case of any FIR filed. Depending on where you reside, you can approach the concerned official and give a written complaint withdrawal letter and police can close the complainant at preliminary stage itself.
In your case since the police is asking for bribes to accept the withdrawal request, you can file a suit against them.
A police officer is treated as a public servant.
Under Section 166, if a public servant does not do what is required to be done by him in his official capacity, he will be punished with imprisonment of a term.
Section 171E mentions details relating to punishment for bribery—Whoever commits the offence of bribery shall be punished with imprisonment of either descripttion for a term which may extend to one year, or with fine, or with both-- provided that bribery by treating (For example: food, drink, entertainment) shall be punished with fine only.
Also, Section 13 of the Prevention of Corruption Act says that a public servant will be liable for criminal misconduct if he habitually accepts or agrees to accept any gratification other than his legal remuneration or dishonestly misappropriates any property entrusted to him as a public servant or abuses his position as a public servant will be liable for criminal misconduct and shall be punished with imprisonment for not less than four years which may extend up to 10 years and shall also be liable to pay fine.
I hope this answered your question.
Have a good day!