How to remove symlinks created after a specific date?
If you want to make sure you only remove the symlinks created you can run
cd /usr/local/include
rm $(cd /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/; echo *)
This does not work if the filenames contain spaces etc., but for this specific case this isn't an issue.
Inspired by How to delete files from a specific date?:
# Create a marker
touch -t 201910190000.00 /tmp/PID$$.marker1
# View the files you would like to delete
find /usr/local/include/ -type l -newer /tmp/PID56680.marker1 -ls | less
# Delete them
find /usr/local/include/ -type l -newer /tmp/PID56680.marker1 | xargs rm -f