In Excel, how do you delete line breaks?
A more Excel way:
As line-break is CHAR(13), you could try something like this (assuming your text is in A1 and you'll put edited text in B1)

B1: =SUBSTITUTE(A1,CHAR(13),&quot;&quot;)

or
B1: =SUBSTITUTE(A1,CHAR(13),&quot; &quot;)


Source: answers.microsoft.com