I created a tree of 217 individuals not related to me, without thinking, within my own tree database. I was smart enough to put all those images, sources, etc, in a separate folder. I plan it as a Christmas Gift. So, I exported an xml of all the people related to the recipient, the planned home person of that tree. Now I can put gramps, this folder and xml on a thumb drive for her. But, I’d like to remove it all from my own database. What will happen if I just remove that folder from my hard drive? Will that cause more problems than it is worth?
You can delete that folder. Then run the check database tool; Gramps will ask you to delete corresponding medias from your db.
But other records (persons, sources, citations…) will still be there if you do nothing to remove them.
An idea before running the check database could be to use/find medias which have file path linked to that directory to help you to find and delete other records of your db linked with these media records (before checking/deleting medias).
Check that your exports are working. Put the xml and media folder on the thumb drive, then create a new family tree and import both. You can delete the new family tree if everything works.
Make a backup of your old tree, so you can always go back if you deleted something you wanted to keep.
Remove all people you no longer need. You could use a custom filter e.g. people related to person to help you to select them.
Run the tool “Remove unused objects” to find and remove events, places, notes, etc. which are no longer connected to any persons. Mark them all and delete them (or uncheck some objects if you want to keep e.g. certain places).
