How to delete the newline characters at the end of every line in Vim?

I have a huge file that I would like to format using Vim. For that, I would like to delete the newline characters at the end of every line.

For example,

I
want
this
to be
just one
line

should become

I want this to be just one line

I was thinking of doing it via the following command:

:%g/^/norm!‹a keyword that deletes the \n›

but I just don't know which keyword might work for that, to automate the pressing the Del key on every on every line.

Thanks in advance!