how can I delete "cancel" reservation entry type Reservation Surplus?
What do you mean? Do you want to remove the ability for users to cancel surplus reservation entries? Or do you need to delete a specific reservation entry of the type surplus already in your database?
I need to delete a specific reservation entry of the type surplus already in the database when I post Inventory Journal
If you need to delete reservation entry, do it safety from source document (where you did reservation).
If it is from posted Item Journal then it was wrong usage of reservation functionality