To elaborate on the comment, you can set visibility settings when loading custom tracks or track hubs directly on the line: https://genome.ucsc.edu/goldenpath/help/customTrack.html#TRACK

There are many arguments you can pass as the track header, for example:

track name=coords description="Chromosome coordinates list" visibility=0

Setting visibility to 0 is equivalent to =hide. Values for display_mode include: 0 - hide, 1 - dense, 2 - full, 3 - pack, and 4 - squish.

If you've already added tracks, you can click into 'Configure' under the browser track display. From here you can 'hide all' or 'show all' for entire categories.