I wasn't clear enough last time even though I got some great responses about security tool I need more help!?

Ok, I already have McAfee and malwarebytes installed on my computer. I went to turn my computer on and Security Tool popped up on my desktop. I have tried to run a scan with malwarebytes but it wouldn't let me so then I tried to start up in safe mode with networking and it won't let me even do that. It has blocked everything from me and won't let me run anything. It won't even let me get into my task manager. I have tried to download rkill and save it to a flashdrive but the other computer is reading rkill as a trojan and won't let me download it. I have tried just about everything imaginable except for clearing off my hard drive. I don't even think I can do that because security tools won't let me open anything to do anything. Does anyone have any other suggestions???? Please help?!!!!!!!!!!!!!!