Yes, you can. You do a backup and restore to the point in time before you downloaded Win 10. If you don't know how to do restore, Windows website can advise you. It's not complicated.
A non-techie friend of mine did the same thing and had the same result. He was bogged down heavily as Win 10 sucks up a lot of resources on an older computer with Win 7. He's fine now.
The restoration will allow your computer to be exactly as it was. you might have to re-add your favorites websites, etc. in your browser.
BTW, welcome back to A2K, Pitter.