Unfortunately this is not possible right now. I will update this thread if we decide to take this up.

I see, I learned that there is no enable/disable user function yet from another forum topic.

But it is possible to create/delete account through api, right?

Yes you can create/update/delete contacts in Freshdesk through the API - http://developer.freshdesk.com/api/#contacts

Thank you.

But if there will be disable(suspend) user function, that would be nice.

I'd like to make membership site that offer support on Freshdesk.