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
Ok, we need a bit more information. Exactly what is your requirement?
Why do you need to delete it? What have you tried before? Have you tried deleting it via reservation entries before you post the journal?
As my suggestion, Dont go for deleting any reservation entries. Because if you want to delete the reservation entry from table level you want to delete the data from 2 or more tables.
So kindly do the cancel reservation from that sales order line page .
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