Error: "Only the file owner [...] can stop sharing"

When I try to stop sharing my RDA file, I get a message that only the file owner can stop sharing but I'm the file owner.

In Sage 50, the file owner is the Sage ID that was used the first time the file was shared on RDA
It's possible to open the file as sysadmin with another user email but only the file owner can stop sharing
If you're the data owner, this means that you used a different email to share the file in the beginning

Make a note of the email on the message.
- This is the original sysadmin email
- If you no longer have access to this email, see:
  How can I change the sysadmin email address (Sage ID) in my cloud connected company?
Click OK to close the message.
Go to File, Connect to a shared company.
Click Yes, when asked if you're finished with the company.
Click OK on the Connect to a Shared Company window.
Click Log in as a different user at the top.
Log in with the email address from Step 1.
Click Cancel as you don't need to download the file.
The file should still be open.
Go back to File, Remote Data Access, Stop Sharing.