How to revert an access denial to a Support Identifier (SI)

Oracle database Enterprise Edition 19.21 running on Red Hat Linux x86

I am the admin of four support identifiers. I received a request to access one of those which I denied because I did not have enough information about the new user. Now that I have I need to revert the original decision and grant read access to it but I cannot find a way to do it.

I have used the tab Grant All SI - but this grants access to three of the four SI, leaving the denied one as it is- denied.

Thanks for any suggestion to solve this issue,