Hello Steammys,
1. I think the warnings stay for the while you are on the server.
If u want to know better about that ask an Admin I am sure he knows.
2. U cant disable SA:MP for a period of time, samp is a program like earch other.
So SA:MP hasnt a function to disable it.
3. U cant go around a IP BAN (ban), if any admin ban you then is your IP banned too.
The IP is the "adress" of you computer.
So you cant change it if he/she/they are on your computer.
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If they want to create a new account on YOUR IP it doest work.
The only solution is, dont let him/her on your account.