Is there a way we can provision access to these forms for additional users

We have developed a robust library of forms under a single account.

Is there a way we can provision access to these forms for additional users in such a way that additional users may have access to SOME forms, but not all under a different credential?

Can that access be centrally controlled in such a way that if we need to disable access to forms by a user, we can do so efficiently?

Have you tried adding sub users to your Main Account? Basically, you can add multiple sub users (depending on your plan) and set up different permissions for each sub user. 

To do so, go to your Account’s Users page. Then click the Create New Sub User button. 

Once you have entered their email address, you need to select the forms that you want to share. 

You can also set permissions either allowing the sub user to View Submissions or Edit Forms. Make sure to click the Create button. 

You can read more about adding sub-users here. 

In case you're wondering, here are the different plans: