On windows to delete all presets in a bank you can do this:
1. Select the bank
2. Select the first preset in the preset browser.
3. Press "Shift" before clibking/ selecting the last preset in the bank. (I aasume a similar thing can be sone on MAC - perhaps using the "Apple" instead of "Shift") All preset will now be selected.
4. Press delete. All selected presets will be deleted and if it's all the presets in the bank, then the bank is deleted too.
(All presets between a first selected preset and a last Shift selected preset will be selected. so you can allways delete more presets at a time.)
I too exsperience issues when importing presets between to PC's. I would like 1. a overwrite and 2 a import only new preset feature.
Also i still get issues when changing attributes on a preset. The preset double up instead of overwriting. ANd if one is being deleted, then both vanish.
I hope everything will be fixed.
EDIT: Perhaps i should add, that i believe you can copy your saved presets from one computer to another without using eksport/ import.
On a PC the presets are located in the hidden folder C/ ProgramData/ Arturia/ Presets/ ...
And it's also possible to eksport/ import single presets. The attributes is stored in the presets.
Hope this help.