This is mostly taken from a thread about removing the front bumper but it as the info.
Go to this webpage:
https://toyotamanuals.com.au/accessoriesPaste this number in: PZQ2989281
Click on 2nd or 3rd one down to download the bullbar fitting guide in pdf and it explains the process of removing the grill.
I've taken a grill apart for a project and the chrome parts can be separated by undoing some screws and carefully prising apart the tabs.