Did GTM+LTM need to remove from sync group before Upgrade HF?

No need to do that. During the upgrade, make sure you have 1 appliance active/operational at a time, put the other 3 in "Forced Offline" state.

 

I'd recommend the following procedure:

 

1) Sync configurations in all sites

 

2) Put 3 standby nodes to "Forced Offline" state. Only the active node of active site should be left operational

 

(license reactivation not needed in case of HF install)

 

3) Install the Hotfix, and once done, reboot all 3 nodes to the partition where the new Hotfix is installed

 

4) Confirm all works as expected, and release the "Forced Offline" state

 

5) Issue a cluster failover in the active site

 

6) Repeat 2,3,4 with the node not yet upgraded

 

7) Sync configurations in all sites