Delaware 5 day notice letter

[John Cimino]

Well, I bought my first rental property and long story short I inherited a bad tenant.  I ended filing for eviction, but was told that the pay or quit letter I found online was "invalid".  Luckily he didn't show up to court and just move out on his own, but I'd like to have a good template for the next time I need to send notice.  Do any of my fellow Delaware landlords have an appropriate 5 day notice template?