I have several labels in the "Move To" dropdown menu, and I'd like to keep the labels but hide some of them. Advice?
You can't. That menu holds all of your labels. The only way to remove a label from that list is to remove the label altogether.
If you're having trouble with finding your more important labels amongst a long list, I suggest changing your label name to have some sort of non-numeric character in the front. I do that with a handful of my labels to make sure they're at the top of the list.
So instead of
Now my "Joe" label is at the top rather than halfway down the list.
You can change the name of a label to make sure that it sorts at the top of the list, a number or and underscore works great.
You can't hide a label from the pull down list but you can make other changes:
When looking at the list of labels under "Move to" or "Labels" You can used the manage labels command to hide a label from the sidebar list
Choose which labels appear in your list on the left: In the "Show in label list" column, click the "show" or "hide" link next to each label to choose whether it will be shown in the left panel of your Gmail pages. You can also set labels to appear only when they contain unread messages (otherwise, they will be hidden).
Choose which labels appear on your messages: In the "Show in message list" column, you can choose whether you'll see each label displayed next to its messages' subject lines. Click hide if you don't want to see that label name when you look at the messages it contains.
Delete labels: If you see a label that you don't want anymore, click remove in the "Remove label" column. (You'll have to confirm that you'd like to remove the label by clicking Delete.)
And one more note, if you have a bunch of sub-categories, it will rename them all. So, if I have a category at the top like
apples and then a bunch of subcategories like
apples\yellow and I add a
z to them, it will add the
z to all of the categories and move them all to the bottom which is handy as well.