There is a Lightroom folder within the pictures folder, and that Lightroom folder contains the catalog and other relevant folders needed for the proper functioning of Lightroom. But the image files are not in the catalog. They are simply in folders on the hard drive. If the computer is "out of space" then your best option would be to add an external hard drive and move your image collection to that external hard drive and update the folder location in Lightroom.
I would say it's more likely to be the images taking up the storage and not your lightroom catalogue. I suggest trying to find when the image are stored and moving them first. Once you have moved the images, you will then need to tell Lightroom where to find them.