How to delete everything in a shape/outline

localnative,

You may try this on a copy, after locking/hiding the original artwork:

1) Ctrl/Cmd+A to select everything, then Alt/Option+Shift+Ctrl/Cmd+8 to Release Compound Paths and Shift+Ctrl/Cmd+G to Ungroup, maybe a number of times of either/both (with the purpose of having only individual paths (you can have a look in the Layers palette);

2) Pathfinder>Unite.

Or you can use the Shape Builder, with a bit of manual merging.

https://helpx.adobe.com/illustrator/using/creating-shapes-shape-builder-tool.html
https://helpx.adobe.com/illustrator/atv/cs5-tutorials/creating-complex-art-with-the-shape-builder-tool.html

Edit: Hi Susan, there seems to be a rift in the space time continuum.

Have you tried Unite in the Patherfinder Pallet?

"I thought maybe I could remove all of the thinner lines but don't know if that's possible?"

If the "thinner" lines are actually stroked paths, you could select one, then choose Select > Same > Stroke Weight to select all the paths with that same weight assigned and then Delete. BUT, it's impossible for us to know whether you've got stroked paths or filled paths, or a mix of both, without seeing the artwork.

"I'm too new to AI and I feel that the answer must be easier than this."

It may or may not be. Most clipart that looks like your example is distributed as one big black-filled compound path; really not meant for the kind of editing you're attempting. Post a screenshot of your artwork, selected.

First of all Duplicate the Layer containing the artwork as a backup and turn of it's visability, so only one Layer is visable.

Next select all (Ctrl/Cmd +A).

Right click and select Group.

Then go Object Expand. 

Now all your stokes and paths will be editable with the Eraser.

I would use the Pen Tool to draw one shape to subtract the unwanted areas with the Pathfinder's Minus Front button.

I hope this helps!

Sim

Start by checking your layers panel to figure out which layers/ groups actually make up the outline and which ones are the inside content. Deleting a huge chunk of those layers may already get you halfway there. for anything beyond that we would need screenshots of said layer panle's structure and the artwork with paths selected to get at least an idea how it may be structured.

Mylenium