Unlearning Research Techs ... Can you?

Is there a way to unlearn or reduce a players current research levels?
I am want to create a out come where a player can upgrade things but the upgrades only last X amount of time?
Right now I cant seem to find a trigger action that unlearns research levels back to 0.

I dont know JASS but with out being able to unlearn researches this map it a lost cause

No.

the most you can do is a negative upgrade, but that only works once

I had the same question, a while back. One possible solution came up:

Alternate your upgrade effects. E.g. Level 1 is your upgrade bonus, level 2 is without the bonus, level 3 is with it... and so on.

That way when you want to toggle it off, just upgrade again to the level that has no effect. 'course this isn't very practical if the player needs to toggle this upgrade often.

The simple answer is No.

The complecated answer is No. You can't.

Theres a number of ways to get around it, some which work well, others which don't. But you can't unlearn upgrades.

Lol. You can but that's a complicated and lame way.
1. Create two separate upgrades.
2. Create two unit-types each one using a different upgrade from ?1
3. Create ability of type "Chaos", binding both units from 2. Note that it must have no requirements.
4. Then if you need to change the level of upgrade add/remove the ability from 3

P.S. That's third time i answer this question. The first one was at xgm, the second one at wc3search at the third one is here.

there is a 'better' way (imho):

make a spot on your map no unit can get to / see. change upgrades into units, move them there when complete, and apply bonuses with bonus mod. then you can simply kill the units and remove the bonuses.