For Windows OS (Win10/11, Server 2019/2022/2025), the MDE files/services/reg keys are built into the OS. Manually deleting these files is not recommended and could put your machines into a broken state if/when you ever want to onboard them back to MDE.
For macOS, you can find more info here: https://learn.microsoft.com/en-us/defender-endpoint/mac-resources#uninstalling