First you do not need to clear the HSA account just because you stop having a HDHP ... you just need to stop contributing to it.
However, if you wish to take money out for non medical reasons and pay the taxes & penalties then do so ... on the return you will report the distribution and the portion not used for qualifying medical expenses will be automatically reported on the form 8889.
You can own and use an HSA for medical expenses tax-free even if you are not eligible to contribute.
Turbotax will ask when you enter the 1099-SA form if the entire distribution amount was used for medical expenses. When you click no, Turbotax will ask for the amounts of qualified medical and non-qualified distribution and you pay income tax plus a 20% penalty on the non-qualified part. So, you're going to lose half the money to taxes if you pull it out for non-medical expenses.