Capital gains tax for siblings

House owned by siblings, one lives in it as primary residence. The other never lived in it. If they were to do transfer of equity and have the name taken off the mortgage of the sibling who doesn’t live there , would any capital gains be payable ?

Hi

If the sibling who is the beneficial owner of the property, pays a sum to their sibling to remove them from the mortgage, then there is no capital gains liability, as the mortgage is only a means to acquire the property.  
It is the beneficial owner who will potentially be liable to capital gains tax on the disposal of the property.  Please have a look at CG10720 - Persons chargeable: beneficial owner onwards for more information.

Thank you