EMB ERJ 145 ER/LR
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Time Pressure; Training / Qualification; Confusion; Distraction; Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
Flight Crew Overcame Equipment Problem
Procedure; Human Factors
We were getting deiced in ZZZ; upon finishing deicing I accidentally turned off the number one engine. We tried to start the APU (Auxiliary Power Unit) twice but we did not have results. We contacted the company and had to be towed to the gate. Lost off power; running on batteries.After reading the checklist I saw the number two engine had to be off. For some reason after we were done deicing I thought the number one engine was off and saw the start stop selector on the run position; I thought the switch was on the wrong position and needed to be off. I selected the start stop selector to the stop position to start the number one engine and that is when I realized that the engine was already running. Deicing procedures is not something that we perform every day. We tried to start the APU to get power back but it didn't work out. We contacted Operations and Maintenance to get assistance. Check the N2 on the EICAS (Engine Indication and Crew Alerting System) before turning switches.  Double check with the Captain before taking decisions and be more aware.
EMB-145 First Officer reported inadvertently shutting down engine during taxi after de-icing.