You can yank them and they will come back from seed next summer. You can trim them to get rid of the unsightly parts and they will come back from the roots this summer and still come back from seeds next summer.

The good/bad of California Poppies is that they look wonderful at times and lousy at others. Best enjoyed from a distance in larger yards or wild meadows. They are tough to get to look good all the time in small urban yards. BTW, they won't transplant at all.

Just cut them back to the ground when they start looking crispy. They are summer deciduous perennials.

And if you ask me, they look good in any landscape large or small.

A similar and even better plant is Mexican Tulip Poppy, Hummannia fumarifolia. Much longer bloom time; reseeds.

When you see new growth at the bottom just cut the old stuff back. I have poppies in the ground that are three years old.

I do have a question about mulch. I will be putting in 3" of mulch and was wondering if the old poppies will grow up through the mulch?I know the seeds won't.