Some printers have a possible build area of (for example) 20cm on the X axis. As this is the mechanical maximum and this edge shouldn't be touched while printing, the firmware settings often have a little bit smaller values, in this case probably 18 or 19cm, for safety.3d printing - fdm technology
I'm pretty sure, that your printer runs Marlin and you should be able to find the firmware of your printer somewhere online. Get the Arduino IDE at arduino.cc and open your firmware. In the configuration.h there should be values dialed in for maximum build measurements, adjust them according to your needs, but first test, how much space you really have, before crushing your printhead into the printer. As the Marlin firmware is quite a giant to read, it might be difficult to find the lines, that you need to modify. You can use the key combination "control + f" to search for a term, like "endstop" or similar, to speed up the search process. Videos like this one will guide you as well.