How to remove Leaves Period (with status accepted or rejected)

Good morning,
I am just instructing my colleagues how to do holidays in PQO. As a result of the test work, however, we approved the leave ... Now I understand that I should test on the employee's test account - but it happened ...
I expect that I could find the appropriate array in the database and manually change the value in some column. However, I understand that this can lead to loss of transaction integrity or even the entire PQO database.
Of course, an additional copy of the database is made.
Asking for your recommendations - try or give up?
Zygmunt