The fix to bug 51739 has made this less of an issue, in that the remove template button can be accessed by scrolling to the very bottom of the list. I still think the button would be better placed next to the "save changes" button though.

Changing from a bug to an enhancement accordingly.

(In reply to comment #0)

*moving the "Remove template" button next to the "save changes" button (which
would probably be more logical than placing it under "options" - see also bug
51135).

The problem is that button removes the single template that the pane is about, not the entire transclusion (which can cover from one template to thousands) - the dialog footer buttons are meant to apply to the entire dialog's subject, not just the bit you're currently looking at.

However, maybe it could be up in the top-right, alongside the name of the template you've currently got selected?

(In reply to comment #2)

The problem is that button removes the single template that the pane is
about,
not the entire transclusion (which can cover from one template to thousands)

the dialog footer buttons are meant to apply to the entire dialog's subject,
not just the bit you're currently looking at.

Ah rights, yes that does make sense

However, maybe it could be up in the top-right, alongside the name of the
template you've currently got selected?

Right aligned on the same line as the template name / parameter name (for remove parameter) does seem like the best. Need to make sure that it doesn't collide with a long template/parameter name though.

The button has now been moved to the right of the template or parameter's name.