I keep getting a warning message that terminal would like to administer my computer whenever I run standard commands, such as editing crontab in Vim. This never used to happen on my old Macbook. How do I turn off this feature?
Please also see Reset All Mojave App Permissions
These are new(ish) security features that have been gradually introduced in recent macOS versions. Apple noticeable ramped up these security controls with the release of mojave.
The system noticed that Terminal was being used to access files that aren't normally edited by end users. (Were you attempting to edit the crontab for the root user? ... i.e.
sudo crontab -e?
The command line utility that can control this is
To reset warnings associated with the Terminal app, you can use
tccutil reset All com.apple.Terminal. This will reset permissions and warnings associated with Terminal back to factory defaults ... but from here you would be allowed to grant permissions to Terminal.