Deleting personal iCloud info from work laptop?
I'm about to change jobs so my existing work laptop (2018 MacBook Pro) is going back to my employer before I move on. With their consent, I've used their laptop for some personal stuff inc logging into my own iCloud account. I've used all of the iCloud apps and capabilities inc password autofill, emails in the Mail app, Messages, Contacts, Calendar, Safari, Photo, downloads etc etc
I don't have full admin rights to the laptop so can't completely remove my user account or flatten the laptop before handing it back.
How do I permanently remove all my personal iCloud data from their laptop before I hand it back? Am I right in saying, if I simply sign out of my personal iCloud account ALL my stuff will be permanently deleted from it or are local files kept on the laptop which could be accessed once I hand it back via specific software programs?
For the record: I mostly used iCloud file storage for my own personal stuff but there will be some personal files etc on the SSD / desktop. Can they also be permanently deleted?
Whilst I have no reason not to trust my old employer, I wouldn't want all my personal stuff being 'restored' through some of the current restore software packages by someone unscrupulous.
MacBook Pro with Touch Bar