How to remove a single file or folder from a backup in Time Machine?

Time Machine integrates daily, weekly, and monthly backups and the risky maneuver of attempting to remove a single file or folder compromises this process. Do not attempt to "edit" your Time Machine backups by removing any content from the backup drive. Time Machine has its own cleaning procedure that you should trust to avoid damaging the backup continuity.

To add, this is especially when the Destination Drive is formatted in the APFS drive format.

Mucking around on the TM Backup drive runs a High Risk of corrupting the Index file TM Backup uses to keep track of all the changes.

Should that occur, everything will be lost.

Then, the only option is to reformat the drive and start a New Regime from scratch

It is no longer possible to delete individual items from the Time Machine back up.

Yes, you do remember correctly. That is why I said it is no longer possible.