Maybe it has a different account set up as sysop? Can you check your user-config.py what username it contains for the wiki you are trying to delete stuff on. Additionally the output of python pwb.py version together with the wiki you edit can be helpful.

srwiki, bot account MilicevicBot, sysops account Milicevic01
version.py output

Do both accounts use the same password? And if not, which account's password are you using?

I used password for sysops account when i tried using delete.py but it reported WrongPass, and i tried agian now and it worked, i gess it is resloved

No, and no i didnt mistype password i used copy-paste just to be sure