I have edited my sidebar to remove the todo list entry because I don’t use it and it is getting rather crowded in there. Every thing is fine until i log in HA the following day and it is back again!
Changes like that always revert when you log in again (it’s only stored locally per session).
Is there a reason you don’t just stay logged in all the time instead of logging back in every day?
I’ve noticed that with add-ons you usually have the option of adding an item to the toolbar. With integrations that appear in the toolbar, you’re stuck with it. 
I’m not logging out but when i look at the dashboard for the first time each day it asks me to login and that’s it the item is back on the sidebar.
Are you checking ‘Keep me logged in’ when logging in?
And is your web browser set to clear everything when you close it?
Are you saying this is not saved in my HA setting but in my browser?
Yes. The companion app will save it, but if you use a browser it will depend on the browser settings.
Seems like a stupid way of doing it and a cant even think of a reason why.
No problem I can permanently remove it using my ad blocker. Thought it may of been a bug.
Thanks for your time.
Settings are stored per device (on the device) not per user. This is handy for having different settings for your mobile, desktop and wall panel displays.