How to remove this passenger side mat - Leak troubleshooting

[ramchol76]

I am troubleshooting my Tahoe passenger side water leak when it rains...

• I already removed the cowl and sealed the HVAC service access cover, which had gaps
• removed the A pillar trim and observed if any leak from windshield - none on the right end

planning to replace the weather strip which has small slack which can pass water from exterior to interior. before doing that, I removed the vinyl carpet (PPV) and notice a mat on the foot rest area (marked in picture). the mat has smooth water proof material on top and foam in the bottom. the foam is really wet, makes me wonder if the water intrusion somewhere below that mat area.

how to safely remove this mat? i dont see where its anchored. btw what is this mat called?

 

[ramchol76]

Any information on how to remove the mat helps... the water leak is coming from underneath