How can I remotely trip a RCCB?
You need an extra option for this

Assuming your EPO switch is a normally open type, the typical way to do this at the panel uses a breaker with a shunt trip or shunt release option fitted, which will trip the breaker when power is applied to the shunt trip's terminals.  Most North American panelboard-type MCBs can be ordered with a shunt trip as a factory option -- however, it's limited in nature, and often cannot be applied to specialty breakers such as GFCIs/AFCIs.

However, what you can do is provide GFCI, GFPE, or AFCI protection for the branch circuits, and put the shunt trip on the main or feeder shutoff breaker.  That way, you only need one custom-ordered breaker instead of several, and also circumvent the incompatibility between specialty breakers and shunt trip accessories.

If you were back home...

If you were on the European system, however, DIN rail breakers are rather modular (compared to North American loadcenter/panelboard-type MCBs), so shunt trips for RCCBs are available as a general rule.  Most can be either factory or field fitted depending on the situation and breaker make/model.

(If you had a normally closed EPO, you'd need an undervoltage release option instead -- it's the inverse function of a shunt trip.  These are not as common as shunt trips, especially in North America although some European breaker lines have restrictions on the employment of their undervoltage release options that aren't present on their shunt trips.)