Most HSA accounts are nothing more than regular checking accounts that earn interest. You can take money out at any time for any reason. However, if you take money out for a non-qualified reason there will be tax consequences.

I have both a debit card and a checkbook for my HSA. I use neither for withdrawals. I pay my medical bills with a points earning credit card and then reimburse myself by doing an ACH transfer from my HSA to my regular checking account, which I then use to pay the credit card.