There's nothing wrong with applying.
There's aldo nothing wrong with withdrawing N-400 if you no longer want to become a US citizen. You can do it today.
Before making a decision, does your country of other citizenship allow dual citizenship? Many countries nowadays are OK with their citizens having multiple citizenships. In many cases you will continue having your citizenship and passport from other country if you become a US citizen. And one outside of the US, you can still use that country's passport to travel if you wish.
What country are you from?