Deleting a table is a data definition language (DDL) operation. Parameter binding is not supported for DDL. Even in an INSERT statement, you cannot use parameter binding to replace the table name.
Use simple string concatenation:
PROCEDURE empty_table(in_table_name VARCHAR2) IS
l_statement VARCHAR2(100)
BEGIN
l_statement := 'DELETE ' || in_table_name;
EXECUTE IMMEDIATE l_statement
END;