How to remove corporate control from an iPhone XR?

My son purchased his XR from his company before he was laid off. Later on aHe purchased a newer phone and gave me his XR for Xmas. I have an iPhone SE-original. I backed up my data on the SE to the iCloud and downloaded it to the XR after doing an “erase all content & settings”. Once completed, my son’ QC s former corporation logo appeared and verbiage stated that the Corp could control all phone functions, websites visited & what apps I could download! I re-erased the XR and put the SE’s sim card into the XR to see if that would solve the problem to no avail!!

What can I do to get rid of the corporate control of my XR?? Should I just go to an Apple store for help?