Remove app on App Store created by previous developer for our company
Send a real letter in a friendly tone to ask them to delist the app.

If that doesn't work, contact a lawyer and get them to send a letter.

If that doesn't work, discuss legal possibilities with the lawyer. This could include letting the developer know that the rights for the app's are yours and thus they have no right to distribute it on the app store (but only if that is really so), and it could include warning the developer that he's infringing on your trade marks or company name (if he is really doing so).