Assuming the "right side" is the side the bolt is on, then go through the gap with an angle grinder and you'll have it cut in few seconds. Alternatively you can drill small holes in the bolt and use these to turn and slide it, till it opens - that will take longer.

The idea of a bolted door is to stop people getting through.

However, if you are thinking toilet doors and young kids, I would suggest you raise the height of the bolt out of reach of kids. From my own experience going back to my "baby" brother, now 60, but when 3 locked himself in my parents toilet.

So when I bought my own house and had children, I raised the toilet door lock out of their reach.

Or fit a bolt that can be opened from the other side by use of a key.

Otherwise, if the bolt is on the RHS with a 1.5mm gap (1/16") and you can actually see the bolt, then you may be able to cut through it with a thin saw blade, powered by whatever, but the bolt maybe hardened steel. good luck with that one.

assuming it don't have a padlock on it. an old wire coat hanger can be bent and with care you can usually manipulate the bolt, and open the door.

A sawzall would do it in 30 seconds. 1.5cm is HUGE.

1 cm metal punch.

use a screwdriver or kick the door

hacksaw blade

You've got a door bolted from the other side. Between the door and the frame on the right side is a 1.5cm gap. How do you unlock the door? The bolt is an ordinary slide bolt, and you can use anything you want, but the door must stay in its present condition.