So, you've decided for one reason or another to trade in or sell your EVO 4G, most likely for the sexy new HTC EVO 3D strumpet you've been eyeing like a hawk for the past few weeks. But one of the lingering problems you may worry about is just how to get all your data erased so that the new owner doesn't have it.
With the stock EVO 4G ROM and a few minutes of work, you can erase most traces that you and your phone ever shared memories.
First off, I am going to suggest you back up everything from your old EVO to your computer, as about 35 minutes from now you might have a change of heart or realize you lost something (such as all the data on your phone).
Step 1: Erase the SD card (and fill it back up again)
The SD card is where all your pictures, videos, and any apps you moved there are stored. Several applications may have been writing to it without you knowing, so it's pretty important to wipe this out.
Connect your HTC EVO 4G to your computer, mount as a disk drive, go to that drive, and delete everything on it. Please verify that you're on your phone's drive and not somewhere else before you start deleting things or you might just end up toasting your computer's operating system. Alternately (in Windows at least) you can right click the drive and choose Format.
In general this is probably enough to stop an unmotivated hacker, but it's still possible to recover deleted files and formatted SD card contents, so for peace of mind copy some large files or directories onto the SD card. The object is to fill the SD card up completely with junk so any data you had there would be overwritten. Then delete those files so the new owner doesn't have a completely full SD card of junk.
Step 2: Factory reset
Boot the phone into recovery after powering it off by pressing and holding the volume down button and the power button until you see the phone start to do something. What should happen is you boot into a menu that will have 5 options, one of which is clear storage.
Highlight this using the volume controls to move up or down, and select it by pressing the power button. After this is selected, you should have reasonably removed most evidence that the EVO was ever your phone.
Keep in mind however that it's possible an application stored some data about you in an area that was not cleared by either the format, the overwrite, or the clear storage. If you feel like you're selling to a spy, your best bet it to shred the phone.
For most, however, this should remove all your contacts, pictures, email accounts / passwords, logins, etc.
IMPORTANT: If you have previously partitioned your card for Darktremor Apps2SD, you will need to re-partition it to remove applications and data that may be sitting on the SD-EXT partition (even if it is no longer in use).