INT 14h,  7Fh    Remove an "external application" function

      Entry:  AL         Code assigned to external application

              DX         Offset of application entry point

              ES         Segment of application entry point

      Exit:   AX         1954h

              BL         Code assigned to application (same as input AL)

              BH         01h - Removal was successful
                         00h - Removal failed

    Removes an application's entry into the table.  Usually so it can remove
    itself from memory. Error return means ES:DX did not match or that there
    is no entry at the slot described by AL.

    An application that wants to remove itself from memory can issue the  7F
    function to remove itself from the table, then, if it is successful, get
    out of memory. If it had to install itself with an INT 14h dispatcher it
    may back itself out, provided no other applications  have been installed
    on top of it (using its dispatcher).