Como dizer "desfazer de alguma coisa" em inglês

Downplayed would do in some cases as in:
I invited a family member who doesn’t live in the best neighborhood to my house and she complained the whole time. She downplayed my house and kept going on and on about how she could never live near so many white people. Mind you, plenty of black people live in my area

As you see, something akin to "sour grapes" comments made by the said family member.

The answer to the other sentence could be "he was putting down my choice" or "he keep putting down my choice", "he started putting down my choice" etc.
When you can't know for certain it is the case (but it's a probability anyway) use "I think I just felt like he was putting down my choices.".

"Ele ficou desfazendo da minha casa."
"Ele ficou desfazendo da minha escolha."

He was being dismissive of/to my house.
He diminished my house.

He was flouting my choice.
He sneezed at/brushed off my choice.

The Beatles had this chaos and anxiety surrounding the band, and George was being dismissive. The Guardian

The information commissioner said the China-owned video app had done “very little, if anything” to check who was using the platform and remove underage users, despite internal warnings the firm was flouting its own terms and conditions. The Guardian

Obs.: "To be flouting" pode significar "estar/ficar desdenhando" ou "estar/ficar infringindo".

Cf. Como dizer "Pôr / colocar / botar defeito" em inglês