Users who can Publish into a Folder in Resources (Assets) also have the ability to Delete any Resources in that same folder.
In Admin > Settings you can restrict the Delete action to ensure that only Admins of the parent folder have the ability to delete Resources within a Folder.
To change the setting; navigate to Admin > Settings and find the Resource Delete Permission option under the Resources - General section:
If the default is changed to 'Admin', the setting will restrict the ability to delete items to Admins of the Parent Folder within a folder structure. This means that Users with Publish-level permission on the folder still have their regular permissions to upload files, but can't delete them.
This setting will apply to all Folders on your platform.
Please note that the Resources terminology referenced above may appear as another name in your platform as these are customizable terms. You can view related terminology here.