Even if you don't want to allow customers to leave bank account information in the cart, it can show up when a user goes to account maintenance to update their account information.

If fields for bank account info are present when a registered VirtueMart user updates account info, you can turn off those fields in the "Manage User Fields" section of the VirtueMart Admin menu.

Just unpublish the field names in "Show in account maintenance" and any other area you don't want them to show.

This works for customizing placement of other user fields as well since there are 35 user fields listed that you can change.