I am not sure how you deleted it. Ask your System Administrator of your School / Corporate / Organisation who initially installed it for you.
Read this article for your understanding --> Install a configuration profile on your iPhone or iPad - Apple Support
Get started using Apple Business Manager or Apple School Manager with Mobile Device Management
To supervise an iPhone, iPad, or iPod touch, you can use Apple Business Manager or Apple School Manager. You can also configure your iOS device to be automatically enrolled in Mobile Device Management (MDM).
This article is intended for system administrators.
You can start using your supervised devices after your organization or educational institution is set up with Device Enrollment. If you need help adding your MDM server and assigning devices to it, use Apple Business Manager Help or Apple School Manager Help. For more information about how to configure MDM enrollment settings during activation, you might need to contact your MDM vendor or use Profile Manager Help.
Check network requirements
When an iPhone, iPad, iPod touch, Apple TV, or Mac enrolls in MDM, the device needs to access the following hosts:
- albert.apple.com
- iprofiles.apple.com
- crl3.digicert.com
- crl4.digicert.com
- ocsp.digicert.com
After enrollment is complete, MDM uses Apple Push Notifications, which require network access.