The device argument is the same as in the add-map command. Please find the argument's description in the documentation of the latter command.
If a function number is given by the function argument, then only mappings with a matching number are removed.
If a base address is specified, only mappings with the matching address are removed.
If both function and base address are specified, only mappings with a matching function number, at the specified address, are removed.
When used in an expression, the command returns the number of removed mappings.