Old question, but for anyone that’s looking to delete data from the database
Standard field names including top level repeaters and other fields with sub fields, there are two fields that need to be deleted
$field_name
'_'.$field_name
for repeater and other sub fields
$repeater.'_'.$row.'_'.$sub_field
'_'.$repeater.'_'.$row.'_'.$sub_field
for nested repeaters
$repeater.'_'.$row.'_'.$nested_repeater.'_'.$row.'_'.$sub_field
'_'.$repeater.'_'.$row.'_'.$nested_repeater.'_'.$row.'_'.$sub_field
the above continues with each nesting level
the following like value will remove all of the fields and sub fields, be careful with collisions with other fields, back up your DB first.
DELETE FROM wp_postmeta WHERE meta_key LIKE '%'.$field\_name.'%';
You should escape underscores as it is a character in SQL that stands for any one character. field_name and fieldXname will both be removed if you do not escape the _
