Legal Question in Real Estate Law in California

You probably mean "on title," not "on deed" - but once a deed is executed and delivered, it's work is done, and title is altered in accordance with the deed (of course, the deed should also be recorded, to avoid later confusion and doubt, but delivery of a signed deed makes it official). Assuming no irregularities in the gift or sale by which you added them, you're almost certainly stuck with them as co-owners, and you can't remove them from title any more than they can remove you. I would note, you can force a sale of the property through a so-called "partition" lawsuit, and if you paid property taxes or necessary repair bills and they didn't, you probably would be awarded more of the sale proceeds.

Finally, I'd note that it isn't clear from you question whether the three of you are joint tenants or whether you are a tenant in common and the daughter and her son are joint tenants as between the two of them. Probably the latter, but with respect to the ownership question it really doesn't matter.