In ORACLE

SELECT REPLACE(REPLACE(YourColumn,CHAR(13),NULL),CHAR(10),NULL)
FROM YourTable


FOR ONE CHAR :
SELECT replace(YourColumn,CHAR(13),'')
FROM YourTable

OR
update YourTable
set YourColumn =replace(YourColumn,CHAR(13),'')

IN .NET 
MyString.Replace("\r\n","")   

or..

MyString.Replace("\r\n",@"\n")

Potential Blacklist
Special control chars 0-31 by Unicode must be handled
White list 
[^a-zA-Zא-ת0-9._] -and punctuation chars by your choice
- this is a start of a regex pattern - [^] -everything that not in the pattern is not allowed.
also can do 
[^\w\s\p{IsHebrew}\p{P}] - not taking accesnt chars like ~^ , not finished , but a start

better handled by StringBuilder with loop through chars than Regex 
(more than 10 times better).just Whitelist of allowed chars and if in range 
like this 

if(c>=a && c<=z)...
  sb.append(c)
else
  sb.append(' '); //replacement char