Have a 10 month old heifer that is 40 days in calf can she be injected to get rid of the calf?

Yes you can. You can use LUTALYSE or ESTRUMATE to abort her calf.

Note that Lutalyse is best used to abort cattle when they are between 5 and 130 days into gestation. Estrumate is best used when cattle are between 5 or 7 (or one week) and 4 1/2 months (or ~140 days) into gestation.

Using Lutalyse after 270 days after parturition should only be used if the cow or heifer is suspected of having a mummified or macerated fetuses, hydrops amnii, hydroallantois, etc.

So you have a choice of using either or of the above "medicines."