Unless here born a lycanthorpe

When in doubt, artificially raise the spells level, including the level the players have to have to learn it. Or limit it to one-use spell scrolls. Or add a material component. Or turn it into “transfer curse” where the caster is inflicted with whatever curses they removed (possibly with some variety of saving throw involved) with disadvantage at 3rd level casting, normal roll at 6th level casting, and advantage at 9th level casting. Or add tiers to curses, with certain minimum spell levels for the spell to succeed.

I have "Curse of Lycanthropy

Can you clarify?

Better yet, why can a Bard learn Bestow Curse but needs magical secrets for Remove Curse?

This spell should involve material components that are consumed in the process, like revivify, etc. Like a gem or diamond of at least 500 gp in value. Curses should be effects that are some what substantial.