I switch on umg on mode Input ui only.
Inside img to turn it off im trying to use - get input key time down \ was input key just pressed \ is input key down - but nothing works, so i cant turn off the umg
sry for my english, it could be bad, hope sceenshots will say what im trying to make)
in fact this is all not exacly what i needed. umg is removing without saving as var. and, tick is hooked up just for testing
what ive found - i had to make umg focusable to keyboar, make focus after creating a widget and in umg itself i overrided on key down fuction
You need to save created widget in a variable and when you use remove from parrent you need place this variable to remove it. If I help you dont forgot to vote this answer 
you should replace the location of “remove from parent” and all it’s logics, to the player blueprint, instead checking every tick if an input was pressed. it’s a bad practise, just as well as performance hit (use event tick as little as possible).
if the problem still exist, please post the new blueprint state as screenshot in comment so i will help you further.
also a tip: don’t use branch to check “is notebook”, instead - just set “is notebook” to true, it will have the same result anyway.