My Netbackup in local drive is increasing daily and made a less space on c:\?

my dear all

Master server NB 7.5.0.5 windows serv 32 bit 2003 r2

daily our C:\ Drive size is increasing and when we check ProgramFiles\Veritas\Netbackup is increasing ,

so what is the procedure that we can decrease its size or move to another drive f:\