Try this:
CREATE OR REPLACE PROCEDURE Easydrop (tableview varchar) IS
table_or_view_not_found EXCEPTION;
PRAGMA EXCEPTION_INIT (table_or_view_not_found, -942);
BEGIN
execute IMMEDIATE 'DROP table ' || tableview || ' cascade constraints';
Exception
WHEN table_or_view_not_found THEN
begin
execute IMMEDIATE 'DROP view ' || tableview;
Exception
WHEN table_or_view_not_found THEN
RAISE;
When Others then
RAISE;
end;
When Others then
RAISE;
END Easydrop;

Or BETTER:

CREATE OR REPLACE PROCEDURE Easydrop (tableview varchar) IS
table_or_view_not_found EXCEPTION;
PRAGMA EXCEPTION_INIT (table_or_view_not_found, -942);
V_OBJ VARCHAR2(30);
BEGIN
Select object_type into v_obj
from user_objects
where object_name = upper(tableview);
execute IMMEDIATE 'DROP '|| v_obj||' '|| tableview || ' cascade constraints';
Exception
WHEN table_or_view_not_found THEN
RAISE;
When Others then
RAISE;
END Easydrop;