Suppose you bet the don't pass line, and
a point is established on the come out roll.
Can you now remove your don't pass bet ?
Yes, you can remove it, but you should not do so.
If the point is 4 or 10, then your probability of winning
is 6 / ( 6+3) = 2 / 3.
So, the casino would be happy to see you
give up your advantage by
taking back the bet you placed on the don't pass line.
If the point is 5 or 9, then the casino's probability
of winning is only
1 - 6 / ( 6+4 )
= 2 / 5.
So, the casino would gladly let you take back your bet.
If the point is 6 or 8, then the casino's probability
of winning is 1 - 6 / ( 6+5 )
= 5 / 11.
So, again it is to the casino's advantage to allow
you to take back your don't pass bet.