You can delete data by type_(3) in act_ge_bytearray.
Here are the types of data stores in act_ge_bytearray.
“REPOSITORY”, 1==>Stores your workflow
“RUNTIME”, 2. ==> Stores Runing processinstance variables which are json form
“HISTORY”, 3 ==> Stores historial data like your history JSON variables value and stack trace .
So you free up data that belongs “TYPE_=3”