wasting one's efforts; rendering one's efforts futile
Idiomatic expression literally meaning 'to boil water and turn it into water', used to describe doing something pointless or self-defeating.
Deleting all the materials you worked so hard to create is like boiling water only to turn it back into water.
A metaphorical phrase combining the actions of boiling water (湯を沸かす) and turning it back into water (水にする), implying a pointless cycle of effort.