TL;DR:: Set up IDE_USER_DIR.

I have to keep my roaming profile on a diet and this means moving a bunch of default directories around. The latest victim is SQL Developer

According to this post, the environment variable to be changed is IDE_USER_DIR.

From the post:

According to documentation, the IDE_USER_DIR is picked up automatically if set, so there should be no need for an additional conf file set statement in any recent SQL Developer release.

If this doesn't work, you may try editing config files around as described in the same thread:

Add the following line to one of your conf files: ide\bin\jdk.conf, ide\bin\ide.conf, or sqldeveloper\bin\sqldeveloper.conf:

AddVMOption -Dide.user.dir=../../.sqldeveloper

The path given is relative to a starting directory of E:\sqldeveloper\sqldeveloper\bin, so the directory containing user-related data will be E:\sqldeveloper.sqldeveloper

Note that the "include" sequence for these conf files is jdk.conf -> ide.conf -> sqldeveloper.conf.

Full credit for this goes to Gary Graham-Oracle.

HTH,