Lowering Crafting Rank?

Back when I'd first started I took cooking to 61 and did the guild test to tier up to Craftsman. Now Im thinking of doing Leather. I know that as I get leather to 100, cooking will automatically go back down; but is there anywhere to lower the cap back to journeyman, so that I dont accidentally skill up one day while Im making a friend a birthday cake or something and ruin my leather?

No.

As I understand it, and I could be wrong, it won't make a difference until your Leathercraft is at 99. Then when you perform a synth to level it up, your cooking will decrease by the same amount.

Later on, if you try and make something that requires a skill over 60 to make, your cooking skill may increase causing your Leathercraft (now at 100) to decrease by the same amount.

Please provide more guidance if I am incorrect in my assumptions.

~Yotevol
Leader of LavitzReborn, a relaxed Sky/Sea Linkshell
Apply at www.lavitzreborn.tk

Yes, there is a way, the guild NPC can cap it for you.
If I remember correctly, you need to talk to the head of your new guild after you've reached 60.1+ (or is it after reaching the next rank after 60?) and they will ask if you want to limit your other crafts above 60.

When you do your 68-70 Test item for Leathercraft you'll be prompet to join thier guild and it will take you back down and cap your cooking if you want.