HOw do i get rid of grass that had grew in my huge plant pot?

[Biglips]

as i remembered that i threw grass seeds on the garden and some got into the plant pot that it was next to the garden but for the past 2 yrs it grew and grew (The Grass).

ive managed to put weedkiller on it and pulls it out but it feels like the whole pot is full of grass! iykwim?

Is there anything in the pot you want to keep? How big a pot are we talking?

Pulling grass is generally not a great way of trying to remove it (as you've discovered) The most effective way to remove the grass will be to remove the top layer of soil and all the grass roots. However, if the grass has been left unchecked for a few years then the pot may, quite literally, be full of grass - in which case it would probably be a good idea to empty it out completely and start again, both to remove all the grass and to put some fresh soil/compost in for the plants you want to grow. If there are plants you want to keep then it may be possible, with care, to tease out the rootballs until you have all plant and no grass, but you may need to make a choice between keeping the plants or losing the grass.

You could keep painting the grass with systemic weedkiller, but it will be a long slow job and you'll still be left with a lot of grass roots in the soil (which will get in the way, even if they're thoroughly dead).