To raze a province, you need to play as a Steppe Horde.

You should add a Razing Mapmode to see which provinces are eligible to be razed.

The default hotkey for razing should be “Z”.

To complete the agenda, you should conquer some provinces from a country, then raze the conquered provinces. The country who used to own the provinces should not be fully annexed.

Originally posted by JukΣboҲ:

This summon wants you to have ANY COUNTRY with the opinion of Raze the Provinces with a score of at least -25.

I can't figure out what to do with this one. Can anyone tell me what I have to do for this summon? I have enacted it at least 3 times and can't figure it out. The wording is awful.

Steppe hordes (and a few other similar governments) can raze non-core owned provinces, lowering its development but giving you monarch points. It is possibly the most powerful mechanic in the entire game.

If you raze a province, any country who has a core on that province loses opinion of you. This opinion loss is what the estate agenda tracks. If you do what MasterYi suggests, conquering a bunch of provinces from a country without fully annexing them (because dead countries don't have an opinion of you) and raze it all (which you should do anyway), the agenda should be completed.

Originally posted by asaipuol:

Originally posted by JukΣboҲ:

This summon wants you to have ANY COUNTRY with the opinion of Raze the Provinces with a score of at least -25.

I can't figure out what to do with this one. Can anyone tell me what I have to do for this summon? I have enacted it at least 3 times and can't figure it out. The wording is awful.

Steppe hordes (and a few other similar governments) can raze non-core owned provinces

Wait, non-hordes that aren't former Timurids can...?

*goes and checks*

Huh, the Teutonic Knights as a Holy Horde (though only whilst Catholic, and cannot raze Catholic provinces) and Sich Rada republics for Zaporozhie and Cossack estate breakaways. No wonder I didn't remember about those. Can't even remember the last time I saw an actual estate breakaway nation.

Originally posted by RCMidas:

Originally posted by asaipuol:

Steppe hordes (and a few other similar governments) can raze non-core owned provinces

Wait, non-hordes that aren't former Timurids can...?

*goes and checks*

Huh, the Teutonic Knights as a Holy Horde (though only whilst Catholic, and cannot raze Catholic provinces) and Sich Rada republics for Zaporozhie and Cossack estate breakaways. No wonder I didn't remember about those. Can't even remember the last time I saw an actual estate breakaway nation.

Pirate republics can as well, with the right T11 reform.
Though OP is almost certainly a regular steppe horde, since this agenda is a tribes agenda and all the other razing reforms give regular estates (or no estates, for pirates).
(Yes I know about the missions that unlock tribes for some regular nations, but none of them start as nomads)