How to delete all lines before a specific word?

Shell Programming and Scripting
1

Let's say we have a file containing:

alllllsadfsdasdf
qwdDDDaassss
ccxxcxc#2222
dssSSSSddDDDD
D1Sqn2NYOHgTI
Hello
Alex
ssS@3

Ok, and let's say we want to delete all words from D1Sqn2NYOHgTI and back, this means
to delete the words (and the lines of them) :

alllllsadfsdasdf
qwdDDDaassss
ccxxcxc#2222
dssSSSSddDDDD
D1Sqn2NYOHgTI

Can this be done? I need actually a command to delete the words before the D1Sqn2NYOHgTI (and itself), because I know the command which deletes empty lines...

2 
sed '1,/D1S/d' file

or:

awk 'f;/D1S/{f=1}' file
3

thx!!!