Edit Phrase?

[Kport]

I've set my forum so unregistered members can't see the forum, instead they see this message:

You are not logged in or you do not have permission to access this page. This could be due to one of several reasons:

1. You are not logged in. Fill in the form at the bottom of this page and try again.
2. You may not have sufficient privileges to access this page. Are you trying to edit someone else's post, access administrative features or some other privileged system?
3. If you are trying to post, the administrator may have disabled your account, or it may be awaiting activation.

I Already know how to replace the 1.2.3 options, however I have no idea on making it so that it don't display 2. and 3. If I leave the phrase empty it appears like:

You are not logged in or you do not have permission to access this page. This could be due to one of several reasons:

1. You are not logged in. Fill in the form at the bottom of this page and try again.

Anyway of editing it completely so it appears as just 1 number/sentence?

[Kport]

Anyone able to assist?