deflate

To remove air or some other gas from within an elastic container, e.g. a balloon or tyre.

To cause an object to decrease or become smaller in some parameter, e.g. to shrink

To reduce the amount of available currency or credit and thus lower prices.

To become deflated.

To let (someone) down, disappoint them, or put them in their place.

deflate someone's ego

Scotland's first match at a men's major finals in 23 years ended in anguish after Patrik Schick's incredible halfway-line goal helped the Czech Republic inflict a deflating opening Euro 2020 defeat at Hampden.