You should have rinsed it out when it was still wet, in that case, you would not have had more than maybe a stain left which most likely would have washed out if put through a wash in the washing machine while still wet.
Now you will have to dissolve the paint in such a way that does not damage the fabric.
For that, you will find specialized solvents (often in sticks or small bottles) in the local stores. Names differ per country and I am not in an English language country.
Ask for the one that does dissolve or clean out acrylic paint or read all the small script on each of the bottles till you are sure you have the best match.
Alternatively, if you have several solvents available, try them out on a test piece you can make for this.
When you have the solvent or are trying out the solvents do not start with the paint but first test them out on a bit that does not show, the inside of a seam is mostly the best option. A separate piece of fabric of the same make is often better but not available.
While working, make sure you do not make the situation worse by allowing the paint to run away, best work on a horizontal workspace and keep blotters at hand to take away all liquidized paint.
And you may want to wash the fabric after a session of work, so you wash away the paint while it is wet, not allowing it to dry on you.