Arduino: 1.8.10 (Windows 10), Board: "Arduino/Genuino Mega or Mega 2560, ATmega2560 (Mega 2560)"
C:\Users\Techno Sales\Documents\Arduino\libraries\LCD12864\LCD12864.cpp:20:10: fatal error: wiring.h: No such file or directory
Multiple libraries were found for "LCD12864.h"
exit status 1
Error compiling for board Arduino/Genuino Mega or Mega 2560.
This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.
The IDE tells you that you have more than one library installed on your computer that use a file called LCD12864.h, so it chooses one, which is this one, I believe.
So first verify that this is the one you want to use (verify the syntax of the functions you call to work with your LCD display). If not, discard it, and the problem will (hopefully) disappear.
If it's the one you want, as it's a very old library, I suggest you use the other one... If you really want to keep it, then remove or comment the line number 20
of the file LCD12864.cpp that is in the library's directory, and try again...