Royvds :
Does anyone knows how to make a program that can remove registery keys?
Or have a tutorial on it somewhere on the web? i can't find one
Microsoft has seen fit to include just such a tool, it's called "regedit". However, one does not wander around the registry willy-nilly modifying or deleting keys without:
a) good reason
b) sufficient knowledge to fix what you will inevitably break
Also, as Ijack has already brought up, if your intent is to manipulate the timeout keys on one or more demos to extend the free usage, then take this elsewhere, such discussion is prohibited here. It's doubtful you'd have any success anyway as the relevant keys are usually encrypted and any tampering will cause total shutdown of the software.