How to remove backdoor behavior?

I found a program used to crack the license of a anti-malware called Emsisoft. When i opened it, the cracking program was behaving as a backdoor. I don't know almost anything about programming. How do i remove this backdoor behavior? The program is a .exe file, which i think i'm suppose to decompile it to remove the backdoor codes.

You'll have to debug and locate the code that is unwanted then either alter the executable to not execute it by something such as a jump etc. or nop out the code entirely.

Use ollydbg (Olly Debugger) and find the unwanted code....If you think the software you're debugging is not a Virus, the you should turn off AntiVirus before debugging. It is not recommended, but if you trust it, then do it.

Do the debugging / code removal in a VM to prevent it from potentially destroying your system as well.