clear deletes variables from a workspace. To delete graphics objects (including uitabs) you can use delete.
f = figure;
tabgp = uitabgroup(f,'Position',[.05 .05 .3 .8]);
tab1 = uitab(tabgp,'Title','Settings');
tab2 = uitab(tabgp,'Title','Options');
delete(tab1);
tab1 = []; % make sure nowhere else will refer to a deleted object
