Obvious questions: how strong are their telekinetic abilities? can they use them to sense how a mechanism works without being able to see or touch it?

They can sense mechanism via touching but they are more likely to break them. And they can control up to 2 tons (best of them) mediocre ones are can control 1-1.5 ton

Those sound like important details that should be editted into the question! "able to lift massive weights and smash things with their mind" is a fairly important clarification to "control objects"!

Welcome to Worldbuilding.SE Alwithstick, glad you found us. Please check out our tour and help center.

This is one of those seemingly simple questions that does not have a simple answer. I hope mine meets your needs.

how are you planning to have food and such brought to the prisoners if they can turn the bowls and utensils into dangerous projectiles?

can they get out using their psychic if i burried them alive?

What do you mean by impure materials? What would be a "pure" material?

What makes you think convenient prisons won't work?

"how to imprison them" — all race??? just a few specimens? how many?

what do you mean by "imprison"? Do they have to be able to do anything (labor)? How many of them are in a one cell? How long are they supposed to be there?

"control objects if they are touching its material" — can they control the very object they touch?

what ı mean with impurity is ,as an example, flesh has all that minerals like sodium magnesium potasium calcium etc so it is way harder to maniplate (like water-mineral water iron ore-pure iron iron-stell)

"Control Objects" how? Can they just make them move, or can they bend/contort/reshape them?

What is the range? Can they manipulate objects 1 meter away? 10 meters? 1 kilometer? The other side of the planet? Can they manipulate objects they can't see? Also, what do you mean by impure objects? They can much better manipulate pure elements than anything else? That is, copper and iron can be easily manipulated, but bronze and steel are harder? If so, a wooden crate may be sufficient.

They can reshape objects

Can they fly? Can they stand on an object and by making it fly, fly themselves?

They can fly by lifting their armor or where they stand

In a medieval age they would be imprisoned in the prison no-one gets back from: in a grave. :p Medieval societies didn't waste too money on prisons.

IT IS NOT MEDIAEVAL TIMES ONLY THING SIMILAR IS TECHNOLOGY THAT IS ALL @Rekesoft

Relevant Wikipedia article: en.wikipedia.org/wiki/Australia

@AIwithstick you added a lot of important details in the comments. Please edit the question accordingly.

Can it be cure with lobotomy and shock therapy? If you don't have the technology for Shock just hand wave Magic shock therapy.

are the way to imprison them must require mechanism or machinery to it ?