I have a old desktop PC I want to get rid off. How do I clean the memory or take it out so no one can access my personal info ?

Re-format the hard disk a 2 - 3 times, without an Operating system it is extremely difficult to acquire any info.

All I have is the tower.

Call your local Best Buy. I took mine by and they erased the hard drive for $10

really ....good idea. Can I just take something out of the tower.

My understanding is (and I may be wrong) is that you have to take the hard drive out and drill holes in it.
All your information is still there even if you reformat a pro can find it. Someone who worked with my cousin did this (on purpose cause she was fired)(reformatted) and erased the hard drive but they did get it all back.

Remove the hard drive and destroy it to be sure, just because they are reformatted, information can STILL be pulled off of the hard drive.
Hard drives are done in tracks, you can erase some with the reformatting, but it does not erase all like they claim.

You can also soak the hard drive once out in liquid for 48 hours, drilling holes will help the liquid get in easier though.

forgive my lack of computer parts and where they are located. So far I have 2 , what look like memory boards I had to unscrew to remove. It's a HP n6330 Pavilion.

I purchased "Safe Erase" disc from Dell. I was told this was the safest way to go!