To link wallets, Head to My Balance > Manage Payments and tap on 'Link Account' to link your Paytm/ PhonePe wallets. Follow the onscreen instructions, authenticate using OTP and done.
To unlink wallets, please Head to My Balance > Manage Payments > Tap the wallet you wish to unlink> Unlink (at the bottom of the app screen) and confirm the unlinking. ✌️
PS: Your Paytm/ PhonePe wallet should be linked to the same mobile number you've used on Dream11.