I will make this short and sweet for you.
If there is something you want to do to all tables in your database, there is a command for you.

I will demonstrate, watch my hands because I cheat. To add a column to every table:
exec sp_msforeachtable 'alter table ? add intGoat int NULL'
To delete a column from each table
exec sp_msforeachtable 'alter table ? drop column intGoat'

And this is how you use this undocumented little gem.

Small print: emphasis on undocumented, aka can go away or change in nature without any warning. Test it on your dev DB before using it.