
Hi @Sam Gray,
You can stop inheriting users' permissions and grant unique permission to them.
Go to libraries settings > Permissions for this document library, click Stop Inheriting Permission in the ribbon. Delete all groups in this page and grant read permission level to those users. Then they will not be able to rename/remove folders. But if the users don't have edit permission at first level, they still have no access to edit at subfolder level.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.