Don't get confused with the GKREG.
There are two type of entry in the DIS-GKREG output, internal and external. Having an INTGW entry assigned (LEGK data for the board CGWB is filled in, GWNO and GWDIRNO match to an INTGW entry in GKREG) is not the same thing as "using GKREG" to dial out. If the STMI has had some historic configuration on it, was configured years ago, or it has been used for SIP-Q, it will have that entry, and will definitely have been using GKREG EXTGW GWNO's to dial out as well. But having a configured GKREG INTGW does not mean you have to use GKREG to dial out.
Dialling out using GKREG means that a profile is not configured on the board, and in the LDAT for the outgoing route you have at least one of the GKREG EXTGW GWNOs configured (GW1 etc in the LDAT). When the call is made to the board, 4K passes the IP of the referenced EXTGW in the setup message, and the board knows where to send the packets.
Dialling out without GKREG means no GWNO is passed in the LDAT, and a profile is activated on the board. The profile contains the IP address (the proxy) so the board knows where to send packets. There are also other SIP configuration parameters in the profile that CGWB knows nothing about, payload type for tones, various SIP signalling options that might be needed that were discovered during test. You don't have those configuration options if you don't use a profile. You also have the security of making sure the board will only handle incoming traffic from the specified proxy IP once the profile is active. It doesn't matter for this scenario if the board has an INTGW configured or not. You might have one due to some historical config, but it doesn't need it. If it is there in GKREG though, I would make sure it is correct for SIP-Q/SIP because having it wrong is likely to cause an issue somewhere.
So if this board was used for SIP-Q you will have an INTGW configured with a GWNO, GWDIRNO that matches CGWB LEGK. That's fine, leave them, you still use the profile to dial out and you don't specify the GW1, GW2 etc in the LDAT. You can't remove it anyway without deleting the board and adding again, and it's not worth the hassle.
Latest loadwares actually specify that for native SIP the profile use is mandatory, it should be deactivated only for lab purposes (you specify whether to use the profile or not in the GUI).
My native SIP trunk here looks like this in CGWB
LEGK DATA
------------------
GWNO = (0)
GWDIRNO =
REGEXTGK = NO (NO)
No reference to GKREG at all. Yours will have something in but it doesn't matter. You still activate the profile.
I assume you still have another STMI in this trunk group that was using SIP-Q. If not, you will have to delete the LCR pointing to the old SIP-Q before it lets you delete/change that trunk group.
It is possible to use a profile for SIP-Q if you want, but you don't need to unless you want to use DNS SRV, because you can put a DNS name in the GUI but you can't put it in GKREG.
Don't forget to change the channels from SIP-Q to SIP in CGWB.