Hi john john,
I tested it locally and be able to reproduce the same issue. Per our research, this is by design.
If you uncheck the delete item permission, the rename option will also be removed from the [...] menu.
If modify the file name through the properties option, a prompt for insufficient permissions is also displayed.
For the second point, please provide more details about remote event receiver. This way we can do more in-depth troubleshooting.
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