In the past I haven't minded the syncing of channels when installing a new channel. I liked that it was immediately available on all Roku's. But I just ran in to a problem.
I have a Roku TV that when I tried to add a channel, it told me I was out of space and I had to remove some channels. This Roku TV is in my basement and isn't watched often. So I had several that I could remove that I don't watch on that TV. I do however, watch those channels upstairs on my bedroom TV. Well, it removed them from my other Roku's. Not all Roku's have the same storage.
How do I remove from a low-storage device while keeping them on others?
Sorry, it's not possible. The only way to have different apps on different devices is to link them to different Roku accounts. That's not much of a problem unless you subscribe to things through Roku since purchases and subscriptions are also tied to the Roku account.
Rokus normally just swap channels in and out as needed. There's a slight delay while a channel that needs to be swapped in again gets downloaded, but it is all done automatically.
When you are told there's no room and must remove channels that's typically an indication that the memory cache on that Roku unit has become corrupted. This can generally be cleared up by restarting the Roku.
Depending on your Roku model you'll find the "System restart" option under "Settings > System > Power", or on models without a Power option, under "Settings > System".
Note: If you have a Roku TV with "Fast TV start" enabled, turning the TV off and back on just puts it into and out of a standby state and does NOT give you a complete restart. Use the menu option above.
If a restart doesn't do it, or if you don't have sufficient control with the remote to navigate the Roku menus, you can also restart by pulling the power plug to the Roku for a few seconds then plugging it back in and waiting for it to restart.