I've seen questions on the forums asking about where localdb stores its database files. Often, the question is about how to stop them going into the C:\Users folder. Clearly, that doesn't seem to be a good spot for them.
localdb stores database files in the C:\Users area by default as it's trying to find a location that the current user will have permission to write to. While I understand the rationale, that's not where most users will want those files.
The answer is to not let localdb pick where the files will go.
Instead of writing:
CREATE DATABASE Sales;
use a more complete command like:
CREATE DATABASE Sales
NAME = 'Sales_Data',
FILENAME = 'C:\SomeAppropriatePath\Sales.mdf'
NAME = 'Sales_Log',
FILENAME = 'C:\SomeAppropriatePath\Sales.ldf'
While you're at it, check out the CREATE DATABASE syntax and examples for other options that might be useful to you, particularly the ones around filegrowth. (Hint: Use a fixed increment, not a percentage) Not everything will work on localdb but most will.