Shell Programming and Scripting

How to delete a particular character in a file and then removing the spaces created by that removal.I am working with a text file containing nucleotide sequences.
I have tried sed command but it replaces N with spaces.

example:I want to delete all the N without creating a space after its removal

Input:
acgtaccctttaaNNNNNNNNNNccta
acaattaNNNacatactgatgactctaa
acatcagtcagtaacgtgtactgatacga

Output:
acgtaccctttaacctaacaattaacata
ctgatgactctaaacatcagtcagtaacg
tgtactgatacga

ankita

Code:

sed 's/N//g' inputfile

Code:

tr -d N inputfile

Jean-Pierre.