Hello,

I am very new to Inkscape and am trying to trace an image. It is just a symbol so I have used the edge detection and what I get is the image I need but there is a black box around it like a border. How can i remove this black box? I have tried selecting nodes and deleting them but it only messes up the image I need. 
I realize there is no eraser tool, but is there a way to just cut out those lines around the image?

Thanks!!!

So it seems "Edge detection" works. 😁

Please use the default settings first which is "Brightness cutoff/threshhold=0,450" and try again.

I tried that and I just get a big black box. ???

I´m now not sure what you´re trying to autotrace: this is from the right image of your screenshot:

Any reason no to trace it manually? it´s just 3 elements!

There must be a border embedded in my original image. How do I trace it manually?! Sorry I'm very new. 

I skipped for now symmetry as I don´t know if it´s necessary:

Thank you!!!!! Amazing help  much appreciated 

@PixelPest I'm sorry to bug you but when i try to trace it auto closes the gap on its own. how do i keep it from doing this? also how are you making the line thicker?! :)

@PixelPest YES!!! thank you! of course, turn off fill. Ok great! :)