this is why i don't want chain guards on my bikes.
you will, apparently, need to remove the drive side crank arm to get the chain back on the chainring.
there may be just barely enough room to sneak the guard off without removing anything but the DS crank arm.
slide it forward with the pedal arm pointing forward, and maybe add a bit of twist, front to rear...?
all that full coverage guard does is make it easier to ignore proper chain maintenance
best plan is to get that guard off of the bike, use tin snips or a disc grinder if needed, and hang it up as a reminder of why they are a bad idea.
if that isn't allowed, then cut enough of the backside away to make future removals possible without a few special tools.
i have seen one of these things that was two pieces, and it slid apart allowing easier removal... it was bent (possibly from a Kick or two!) just enough that it nearly DIDN'T come apart....
imagine having the chain drop off as you're dealing with a flat tire, at night, and you are a complete novice working with minimal tools and knowledge.
good luck, and walk away if you get angry.
come back an hour later.
