Drop all databases from server

You can do this through the SSMS GUI. Select the Databases node then F7 to bring up Object Explorer Details, Select all databases that you want to delete, Hit “Delete” and select the “Close Existing Connections” and “Continue after error” options.

Alternatively through TSQL you can do

EXEC sp_MSforeachdb '
IF DB_ID(''?'') > 4
BEGIN
EXEC(''
ALTER DATABASE [?] SET SINGLE_USER WITH ROLLBACK IMMEDIATE
DROP DATABASE [?]
'')
END'