In a shared environment you typically don't have access to delete your database, and recreate it for fresh installs of your product.
I managed to find these scripts which should help you clean out your database.
Use at your own risk.
Delete All Tables
--Delete All Keys
DECLARE @Sql NVARCHAR(500) DECLARE @Cursor CURSOR
SET @Cursor = CURSOR FAST_FORWARD FOR
SELECT DISTINCT sql = 'ALTER TABLE [' + tc2.TABLE_NAME + '] DROP [' + rc1.CONSTRAINT_NAME + ']'
FROM INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS rc1
LEFT JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS tc2 ON tc2.CONSTRAINT_NAME =rc1.CONSTRAINT_NAME
OPEN @Cursor FETCH