Create a new nsec. You have to trust anybody you share it with.
Assume ZBD has your nsec forever. You cannot remove it.
Discussion
So this is the downside of this so called "decentralized" social media app. It can easily be made centralized by scammers like zbd app.
The real downside is you did not understand the sensitivity of disclosing your nsec. Sec is short for SECRET. Responsibility is yours.
But we can't deny that the real scammer is the zbd app since they don't delete my data and my zbd account no matter how hard i request them to delete all of it.