That is a very unusual request considering most desire more xp orbs to level up even faster.

I think if you want kills and to xp up very slowly you will have to accept the unique campaigns that actually help players level up quickly that also drop xp orbs. Kill very slowly and try to avoid picking them up.

It is a difficult ask just to disable the xp orbs alone considering, if you want to level you either want xp or none (to stop levelling up)

Not just no xp from orbs alone, which is a very different request.