Just saw that you said your computer was being slow.

1. Jot down all the programs you have installed that you care about.

2. Backup important files but sacrifice folders like the download folder, the desktop and other dumping grounds.

3. System restore: https://support.apple.com/en-gb/guide/mac-help/mh27903/mac

Note that you may want to follow one of the links in the important section at the beginning based on your mac model.

4. Re install apps as you see fit from your notes.

5. Restore your files.

This can be a theraputic thing for many people and anything you lose that you forgot about is likely something you can rebuild. In many cases, you may decide you didn't need it anyway.