you exuast to the room the tent is? if you bought a dehum it has to be larage enough to control that room's cubic feet. So, it doesn't have to be in the tent.
You could heavily defoliate / prune lower growth... that would also reduce RH. Exhausting to a different area not attached or easy flow back into the tent's room, and that too will help greatly.
i don't know what would be better... reducing canopy evenly acorss entire thingn to get RH under control or removing na plant. I'd wager the even distribution of defoliation wil be better.. less proportion of larf and similar yield, if not better because you aren't losing sq footage of canopy. Target a shallower canopy depth. Take off in waves and see how it affects RH so you can maximize what you do keep.
get a dehum.. use it in that room. it is an option. it's the better option, unless you only grow in seasons that don't result in this dangerously high RH for developed buds. I don't grow in the spring/summer for this exact reason. My climate requires less effort to maintain a good range if i grow in fall/winter. So, i scaled up to match fewer grow cycles, which comes with it's own cost savings and increased efficiencies too.