Windows
3.6.14
Joplin 3.6.14 (prod, win32)
Device: win32, Intel(R) Core(TM) Ultra 7 265K
Client ID: 76b150997bdf459b87f11bf21ad50c3f
Sync Version: 3
Profile Version: 49
Keychain Supported: Yes
Alternative instance ID: -
Sync target: (None)
Editor: Markdown
Revision: 7e2765a
I want to remove Tags and Synchronization from the left sidebar. Does anyone know how to do it?
Noone?
@rhinjard welcome to the forum.
There is almost certainly a better way to do this with CSS 
As you have not had a reply after a couple of weeks I quickly looked for something for you to try. All I have done is use the development tools in Joplin to find a couple of CSS selectors that appear to work.
Put the below in your <home>/.config/joplin-desktop/userchrome.css file and fully restart Joplin (File > Quit).
div.resizableLayoutItem.rli-sideBar > div > div > div:nth-child(2),
div.sidebar-header-container {
display: none;
}
I have assumed that you do not have any tags. If you do, ensure that the TAGS section is rolled up before you apply the css.
For me the TAGS and the sync area both disappear. I haven't had any time to test this. If things start displaying in an odd way as you use Joplin it has not broken your install. Just delete the above css from the userchrome.css file and fully restart Joplin.
A brief intro to how I found these selectors can be found here:
That worked! Thank you so much.