How to quickly delete files of a certain extension in Finder

I used Bluetooth to copy a huge number of files from my Sony Ericsson P1i smart phone to my MacBook Pro, and realized I needed to quickly delete all files with the THM extension.

In the Finder, I see these files:

Next, I narrow down the list of files in this folder to those of THM extension by entering .THM in the search bar of the Finder window.

You also need to ensure that the current folder is selected (rather than This Mac).

Now that you have the desired files filtered and listed, simply perform a Select All using CMD + A. You can also select Select All from the Edit menu.

The final step involves moving your files to the Trash.