LTS advice - outsourced setup

Dear LTS team and forum readers,
I have recently contracted a company to setup a small network in my place, with UI equipments (UDM pro, some APs, couple of access switches and some cameras). The company will do the cabling and the racking/fixing, yet I was wondering, to test the setup, they would have to turn the power on and connect into the UI products. Unlike some customers of LTS, I am not after managed services, what would be the best way for that company to test (I suppose as admin) the setup/tune etc. yet afterwards release the entire access to me ?
Thank you !!!

Once the system is setup have them give you the log in credentials.

Dear Tom,
Thank you very much, I was just concerned the machine names or records would be tampered at UI itself.
Have a great day ahead !