You can hide the system database in SQL Management Studio following Way that I have mentioned below.

Navigate Tools-->Options-->Environment-->General and choose "Hide system objects in Object Explorer".

You can hide the system database in SQL Management Studio following Way that I have mentioned below.

Navigate Tools-->Options-->Environment-->General and choose "Hide system objects in Object Explorer".

OR

In the SQL Server Management Studio, Right click the server and click "Properties". Click on "Permissions" and then select the "Public" role and remove "Grant" from "View Any Database".

Or You can use

USE <YourDatabase>

ALTER AUTHORIZATION ON DATABASE::<YourDatabase> to <Login>

USE MASTER

DENY VIEW ANY DATABASE TO <Login>