remove space

File A.txt

A005           -119.5                -119.5                -100.5
A006           -120.5                -119.5                -119.3
A008                0                     0                     0

Output

A005     -119.5       -119.5       -100.5      
A006     -120.5       -119.5       -119.3      
A008     0            0            0     

I'd first look at what are white characters. Are they spaces, tabs, something else?

cat -A A.txt

or

cat A.txt | od -c 

if your system doesn't support -A option.
Then

sed 's/  */    /g' A.txt

where you substitute the first two spaces with your white characters that are in the file.
//============================================
Alternatively, if you have only 4 columns, here is an awk + printf solution:

awk '{printf("%-10s%-10s%-10s%-10s\n",$1,$2,$3,$4)}'  A.txt

Change 10 to how wide you want the columns.