Old heating timer with new Nest

Hi wondering if you could advise on something for me. We bought a Nest smart thermostat that came with installation included. The man who installed it said the old HW&CH timer in the kitchen was now obsolete as a timer but was being used as an on/off switch for the nest controller which is situated in the airing cupboard. Specifically the CH should be left to 'on' and everything else is done via the Nest thermostat. We are having our kitchen re-done this coming week and I'd love to not have the ugly old timer on the wall. So my question is: can the electrician take the timer off the wall and replace it with a basic on/off switch? My thinking is that if all it needs is power to the unit in the airing cupboard it could be swapped but as I'm not a heating engineer I would hate to screw up the boiler. Especially when it's this cold! Thanks again