how soon can I get my hair colored after I've had a Brazilian blowout?

You have to wait two weeks after your Brazilian blow-out to colour your hair because the brazilian blowout puts a protein protective layer on your hair, so the color wont be its true colour because of that protective layer and it wont penetrate. wait one more week to color your roots/grays. If it is needed to color where the solution has already been applied, you should wait at least two to 3 weeks before coloring from the original day of getting it, not because of damage, but because the blow out has covered the hair and it is hard for the colour to penetrate the cuticle when it is fresh
In the future colour your hair right before you do a brazilian blow-out because it will lock in the color and keep it from fading as fast. The treatment should not have been applied to your roots anyway you should always time your blowout for the same day after color or at least the week before as this also seals in the colour, locking in shine, and make sure that they use the shampoo that is for the blowdry and the serum or the mask after the colour . when you get your roots coloured it should only be the new growth that is coloured, which does not have the solution on it.

I did a color direct after a brazilian.... the hair really feels hard, what should i do?

can i use a dye remover after i ve had a brazilian blowout?

Not sure about keratin based Brazilian blow dry, I use Kebelo, we usually allow just 2 weeks, just remember when you have your colour treatment to use your sodium free aftercare.

Wait as long as u can ! Idealy you should colour your hair as close to before the BKT as you can as the keratin locks in the coour and also works best on chemically treated hair.
Any colour you use now will shortan the life of your BKT as the colour has to open the closed cuticals to get into the hair, if you really do have to colour it just do your roots to minimise dammage to the BKT.