Here's how you can do that:
On the Website: https://youtu.be/RtBTXig7Xjo
On the App:
Home page → Mutual Funds (either from the center of the screen or from the bottom tab) → The goal from which you want to withdraw → More → Redeem → Select any reason for redeeming → Either enter the amount you want to redeem or use any shortcuts such as Redeem all, Redeem All Exit load free, etc. → Review and Confirm Redemption.
Note: If you have not invested in Stocks & ETFs, then you will be on the Mutual Funds page by default.
In case you wish to redeem from any particular funds of your choice, you can refer to this FAQ.
If you wish to check by when the redeemed amount will get credited to your bank account, refer to this FAQ.