This tutorial is based on BlueStacks App Player for Windows v 0.9.0.4049.
1) Click / Tap on All Apps to find the Settings App
2) Click / Tap on the BlueStacksSettings App
3) Click / Tap on Advanced Settings.
4) From the Setting Menu select/Click on the account you want to delete(Below we have shown how to delete a Google Account).
5) After clicking the Google option you will get the list of all the Google accounts present on the app player, now click on the Account you want to Remove.
6) Click/Tap on the 3-dot Icon as shown below and you can delete the account by clicking the Remove Account option as shown below.
How to Add an Account to BlueStacks?