Unknown URL associated with my domain

[raheel]

Hi
i keep on seeing Unknown URL associated with my domain,
for example.

abc.com (it is my domain)

abc.com/xyz ( "xyz" these do not belong to me) giving 404 error

i have to delete almost 10-20 of them via google URL removal service every day,
can anyone please guide how t get rid of these

website platform: wordpress

thanks in advance