On the bottom right you can search for commanders by their skills.
So you can limit your search to LCDR's and pick an ability for that specific position on a ship.

But yes searching for commanders should be audited 

Hi all, I can't remember how many years ago I last actually had a ship fire at something, and it seems that I've forgotten stuff.

I've just had a lone spoiler attack my commercial fleet based at Earth, where I had a Monitor ship and an STO based. At first nothing fired back (spoiler was in orbit so in range of everything) - but then I manually toggled enemy to hostile (who knew - it was killing ships!) and the STO engaged, but the Monitor not. What might I have forgotten to do in order to get the Monitor to fire? I attach the monitor specs, but I don't think I forgot any of the basics (weapon, FC, PP)

Denethor class Monitor      2,618 tons       106 Crew       404.6 BP       TCS 52    TH 15    EM 0
286 km/s      Armour 3-16       Shields 0-0       HTK 26      Sensors 0/0/0/0      DCR 2-7      PPV 17
Maint Life 7.12 Years     MSP 193    AFR 27%    IFR 0.4%    1YR 7    5YR 100    Max Repair 50 MSP
Commander    Control Rating 1   BRG   
Intended Deployment Time: 48 months    Morale Check Required   

Rolls Royce Hobbit II M-NPE-125T15 (1)    Power 15    Fuel Use 87.69%    Signature 15    Explosion 7%
Fuel Capacity 100,000 Litres    Range 7.8 billion km (316 days at full power)

Lockheed Kinetics Firestreak 20cm HCG V40/C3 (2x4)    Range 128,000km     TS: 2,000 km/s     Power 12-3     RM 40,000 km    ROF 20       
Lockheed Kinetics Pepperpot 10cm CDCG V40/C3 (1x4)    Range 40,000km     TS: 2,000 km/s     Power 3-3     RM 40,000 km    ROF 5       
GE Narrowbeam BFC-AM R64-TS6000 (1)     Max Range: 64,000 km   TS: 6,000 km/s    ECCM-0     84 69 53 38 22 6 0 0 0 0
Marconi Spark BFC-LR R128-TS2000 (1)     Max Range: 128,000 km   TS: 2,000 km/s    ECCM-0     46 42 38 34 30 27 23 19 15 11
Hitachi Power PBR R5 (2)     Total Power Output 10    Exp 5%

GE Broadbeam  AS18-R100 (1)     GPS 1000     Range 18.5m km    Resolution 100
Ferranti  AS41-R100 (1)     GPS 5000     Range 41.4m km    Resolution 100

This design is classed as a Military Vessel for maintenance purposes
This design is classed as a Warship for auto-assignment purposes

When designing survey ships I prioritize minimizing the demand on my most valuable resource, i.e. time. I end up building ~10k-ton ships including both geo and grav survey modules, a jump drive, long endurance, a science dept, and 3 to 4 box launchers with slow 1b km range probe missiles that I use on planets that look too nice to be uninhabited. I turn these ships on auto so they survey points/bodies, then look for a new system requiring grav survey, with standing orders to return for refuel/overhaul if they hit deployment time or go below 30% fuel.

This results in a largely automated capability that slowly but surely expands the borders of known space with little input from me, other than sometimes reassigning one to a specific system of interest.

What would be the best way to remove these commanders?
The problem is that I find no way to focus the left tree on the commander to remove.

I'm not fully at ease, gameplay-wise, with using small civilian ships with infinite autonomy; it feels abusive. It's acceptable if it's a freighter of 40,000 tons—you can imagine complete recycling of resources and enough spare parts—but here... IDK!