Hello RobertFMC,
Sorry for the delayed response and inconvenience caused. As per the description above, you want to remove the Digital Signatures, is that correct?
You can clear/remove a Digital Signature if you are the signer, that is if the digital ID with which you did the signing is available to Acrobat.
If you have forgotten the digital ID password you can detach it. Please navigate to Edit -> Preferences (Win), or Acrobat -> Preferences (Mac), then select Signatures -> Identities & Trusted Certificates -> More, Click on Digital ID Files, select the one you want to Remove and click Remove ID. After that, you can delete the .pfx file.
Note: You can only remove your Digital IDs. There is no such option to remove Digital IDs of other users from a PDF using Acrobat/Reader.
To know more about Digital IDs, you can refer to Adobe article Digital IDs in Acrobat
Feel free to update this discussion for any further assistance.
Regards,
Anand Sri.