Where you live miss gundeep? Does it matter to have your hair colour dyed occasionally or permanently? I believe you're not committing any crime or doing anything wrong against Sikh religion unless you hurting someone's feelings. Don't worry just do it.
tell ur father that we are in 2016 not in 18th century, tell them about amritdhari peoples who eat and drink nonveg and alcohol, tell them that inner cleanness is more important then outer showoff #Peace