In our company I have just a client with 100GB disk space.
After using Katalon Studio over a year and updating it, I found out, that the updates are still stored.
I found out they are stored in the following folder: [Install-DIR]\configuration\resources\update
After removing the folders of old versions (5.1-6.2) I got 3.2 GB more free space back.
Maybe this hint helps someone too?