I contributed around 10K with no employer match. I changed jobs in the mid year, now the I have new 401K with Match. I want to max it out so I can get the match in full. How do I take out the contribution from the last employer since there was no match? I still have 3 more months to sort this out.
You contact the custodian and ask for an excess contribution withdrawal.
However, there's a decent chance that the custodian will refuse, since you have not in fact contributed in excess. I know of folks in a similar situation such as yours where the custodians refused to remove the former employer contributions since the excess only happened (if at all) at the latter employer. I also know of folks who were in fact able to withdraw earlier contributions. YMMV.