Learn how to delete all animation in Blender.
We will be using the Action Editor to delete animation, here are the steps.
1) Launch your Blender. I am importing an FBX file which has animation in it.
2) Click on the Animation tab (on the top)
3) Change the pull down from Dope Sheet to Action Editor
4) From the Animation playback menu (somewhere in the middle of the Blender windows), click on the x to delete all animation.

You do not have to keep a T Pos if you do not like it. If you want to keep certain pose from the animation, change to the pose that you like and go to the Action Editor after clicking on the Animation tab and delete all animations.

I hope this helps!

Reference

• How do you make animation appear then disappear?
• How to delete an action?
• Blender 2.9 – how to delete animation action?
• Can not delete actions in action editor even with Shift + x