Can hackers leave behind viruses and can they delete software such as dell support centre?

Something just happened to my computer. Dell support centre suddenly popped up and said executing and then all the important files came up and it it said deleting. Please help. This happened when I was on Facebook.Can hackers leave behind viruses and can they delete software such as dell support centre?Dell Support just did an update. They deleted files they did not need on their program and updated it. It just updated mine about an hour ago.