1
When he starts talking about football, I just disconnect myself. It’s so boring!
When he starts talking about football, I just switch off. It’s so boring!
Switch off can mean ‘stop paying attention’: ‘I switched off and started looking out of the window.’
We normally use disconnect when a physical or electronic connection is broken: ‘Disconnect the computer from the electricity supply.’
2
Tonight, I need to disconnect of work.
Tonight, I need to disconnect from work.
Tonight, I need to switch off from work.
Use disconnect from something, not disconnect of something.
Disconnect from work and switch off from work mean to stop thinking about work and relax. We can also use switch off without from: ‘I find it difficult to switch off after work.’