Help with a silk screen image for t-shirts.

[mermoney]

Celebrating a pandemic birthday and want to send out shirts, as I don't know how many of my friends will actually be able to attend.

I have an image and would like to get rid of the purple area on the bottom and have the background all the same.
Anyone want to try and tackle this?
I am posting this from my phone so I have no idea if the image is big enough for a T-shirt front. Do I have to post this from my laptop?