vim find replace regex

Try to remove \n before the last "
Update:
"B160102","4-Nitropicolinaldehyde","108338-19-8
"
To:
"B160102","4-Nitropicolinaldehyde","108338-19-8"

:s%/-[0-9]\zs\n"\ze

\zs and \ze to set the start and end of a pattern.