How can I remove Applications from Security & Privacy? Is it possible to completely remove apps from the various privacy categories in System Preferences?

System Preferences > Security &amp; Privacy > Privacy
To remove all apps from a particular Privacy category, open Terminal.app and type the following command, then type the Return key:
tccutil reset CATEGORY

where CATEGORY is one of:

Accessibility
AddressBook
AppleEvents (i.e. Automation)
Calendar
Camera
Microphone
Photos
Reminders
ScreenCapture (for the Screen Recording list)
SystemPolicyAllFiles (for the Full Disk Access list)
SystemPolicyDesktopFolder
SystemPolicyDeveloperFiles
SystemPolicyDocumentsFolder
SystemPolicyDownloadsFolder
SystemPolicyNetworkVolumes
SystemPolicyRemovableVolumes
SystemPolicySysAdminFiles

If you want to remove only a particular app, you need to first determine its Bundle ID. Once you know that, issue the command:
tccutil reset CATEGORY BUNDLEID

Note: Specifying an app's Bundle ID appears to require macOS Mojave (10.14) or later.
You could also remove all apps from all categories:
tccutil reset All

Though this might freeze your Mac on macOS 10.15 and later, see comment below.

In the example given in the question, the following commands would remove Terminal and Chrome from Calendars.
First, determine their Bundle IDs:
osascript -e 'id of app &quot;Terminal&quot;'

shows com.apple.Terminal. Same for &quot;Chrome&quot; gives: com.google.Chrome. Now we can reset them:
tccutil reset Calendars com.apple.Terminal
tccutil reset Calendars com.google.Chrome

Pro tip:
This is a one-liner doing the same:
tccutil reset Calendars `osascript -e 'id of app &quot;Chrome&quot;'`

More info in this blog article: Managing Mojave’s privacy protection: Privacy controls.