The IRS requires that you complete form 8880 if there were any contributions to your HSA or distributions from your HSA in 2018. Contributions includes carryover of previous excess contributions that were not withdrawn in time.
Being under HDHP coverage is not a requirement to add the 8889; it is only a requirement to be allowed to contribute to an HSA.
So, if anyone made any contributions to your HSA (like code W in box 12 of your W-2) or if you carried over excess contributions or if you spent money out of the HSA (usually for medical expenses), then you need to complete the HSA interview to add the 8889 (do a Search for hsa (lower case) and jump to it), even if you don't have HDHP coverage.
Otherwise, you don't have to complete the HSA interview. However, based on the input that you have already made, it's possible that TurboTax is convinced that you need to add it.
If you really had no activity in your HSA account in 2018, then do the following to delete the HSA data in the return:
1. make a copy of your W-2(s) (if you don't have the paper copies)
2. delete your W-2(s) (use the garbage can icon next to the W-2(s) on the Income screen
*** Desktop***
3. go to View (at the top), choose Forms, and select the desired form. Note the Delete Form button at the bottom of the screen.
*** Online ***
3. go to Tax Tools (on the left), and navigate to Tools->Delete a form
4. delete form(s) 1099-SA (if one), 8889-T, and 8889-S (if one)
5. go back and re-add your W-2(s), preferably adding them manually
6. continue your return.
