One can generate many wallets from Bitcoin Core GUI, but for each one generated, a new folder appears with its name which contains few files.
Still, if you delete those folders, but maintain the wallet.dat file in the main Bitcoin Core folder, they will appear and you will be able to switch into them from Bitcoin Core GUI.
The question is whether deleting those folders can somehow compromise those wallets. E.g. Are the addresses generated before such folder deletion will 'perform' in exactly the same way as they would if the folder would still exist?
Another way to look at it is, if you just backup the wallet.dat files without the folders of the wallets you created, will that be enough for keeping and spending your BTC, or do you need to backup those folders too?