Uninstalling properly.
WHY IT MATTERS
An abandoned installation is unpatched software sitting on your account. It is a common route into hosting accounts, and it consumes disk and inodes.
IF INSTALLED BY SOFTACULOUS
Use Softaculous > Installations and remove it there. It deletes the files, the database and the database user together, which is tidier than doing it by hand.
IF INSTALLED MANUALLY
- Take a backup first, in case you need anything from it.
- Delete the application directory.
- Delete its database in cPanel > MySQL Databases.
- Delete its database user.
- Remove any cron job it used.
- Remove any subdomain created for it.
- Check for files it wrote elsewhere: cache, logs, uploads outside its directory.
AFTERWARDS
If the application had a public URL, redirect it to something relevant rather than leaving a 404.
WHAT PEOPLE LEAVE BEHIND
Databases, which continue counting against plan limits Cron jobs, which keep running and generating errors Subdomains with no content
Check for all three.