Why Variables In A Alter Or Drop Does Not Work.

I am writing a procedure to drop a specific user's schema only. I select all his/her table name and foreign key in a temp table first and then use a cursor to get the table name and foreign key, and begin drop foreign keys and drop table. However, sql think it is wrong with the syntax like "alter @table_name". Does anyone have a clue, what is wrong with my syntax. Or someone know how to drop one specific user's schema only (Other user may have same table in the database, and you don't want to drop that.

Attached is my scripts: please correct it. Thanks.

CREATE procedure sp_drop_schema @user sysname
as

select o.name table_names, o.id table_id, s.parent_obj Key_id, s.name key_name, u.name users_name
into #temp1
from sysobjects o inner
join sysobjects s on o.id=s.parent_obj
join sysusers u on o.uid=u.uid
where s.type='f' and u.name=@user

declare cur_f cursor
for select table_names, key_name

declare @table_name varchar (80), @key_name varchar (80)

open cur_f

fetch next from cur_f into @table_name, @key_name
while @@fetch_status=0 begin
alter table @table_name
drop constraint @key_name
fetch next from cur_f into @table_name, @key_name
end
close cur_f
deallocate cur_f
drop table #temp1

select o.name table_name, o.id table_id, o.uid users_id, u.name users_name
into #temp2
from sysobjects o
inner join sysusers u on o.uid=u.uid
where type='u' and u.name=@user

declare cur_temp cursor
for
select table_name
from #temp2

declare @tab_name varchar (80)
open cur_temp
fetch next from cur_temp into @tab_name
while @@fetch_status=0 begin
drop table @tab_name
fetch next from cur_temp into @tab_name
end
close cur_temp
deallocate cur_temp
drop table #temp2