System process null high CPU usage or bitcoin miner

Apr 14, 2018
Guys, I just encountered an issue actually I downloaded an infected file which when I runned installed multiple applications on my computer and made it slow after then I uninstalled every one of them from c drive but they posed a serious problem that my CPU usage suddenly started to gain by alarming levels and in the task manager it showed that a system "null" process is going on

After I searched through internet I found that I could be bitcoin miner virus so I downloaded a bitcoin virus remover but it didn't work .
I have Norton security so it suggested me to run its Norton power eraser to eradicate viruses and it even detected them, someof them were named as svhost so I cleaned it and restarted but after restart the problem remained so thought of formatting my computer but soon after all of a sudden it went .

Will it come again and start using my CPU and memory and how to be safe