Closing your watercolour palette when your paints are wet is okay - but here are some tips to keep in mind.
Done painting, and want to pack up...but have a bunch of wet paints? Don't worry.
Clean away any excess water or paint from your paint pans (the individual slots holding each colour in your palette) - you can use tissue, cotton, or a cloth if you don't mind getting it dirty. Then you should be good to go! Just close the lid gently, and you're ready to pack up.
Pro tips: Dap gently at any excess water or paint. Don't rub the actual paint hard or you may lose some/waste it.