If you run the cli command sfdx force:org:list and see a bunch of old orgs you recently authorized or scratch orgs that you no longer use.
You can easily clean them up by logging off from the org.
sfdx force:auth:logout -u <alias>
You get this confirmation screen and important reminder if you want to reuse your scratch org you must know the pasword before logging out.
If you don’t need the scratch org you can delete them with the command below.
sfdx force:org:delete -u <alias>