how to reset device management?

how can i eliminate these "mobile device Management" restrictions from my former employer in my Iphone 11 myself?

I left my company and kept my work phone, however there are certain restrictions in "Setting - General - Device Management > mobile device Management" from my former company that I can't erase. I have eliminated all company owned apps and signed into my personal account but those restrictions are still there. My former company IT administrator is not helping with this. how can i eliminate these "mobile device Managemet" restrictions it myself?