I don't think that the two are compatible. In other words, you can't just switch from one to the other without creating serious problems for the pool.
And I agree with what others have said . . .avoid the cheap stuff at Walmart, etc. Go to your local pool store and pay for the good stuff. It is a bit more expensive, but you won't regret it . . .
Linky thingy
Switching From Bromine to Chlorine:
If you wish to switch from bromine to a chlorine disinfectant and stabilizer for an outdoor pool or spa, the bromine concentration already in the water will interfere with cyanuric acid's ability to inhibit chlorine degradation by UV light.
To switch from bromine to stabilized chlorine treatment, pools must be partially or fully drained and refilled until they contain under 0.2 ppm of bromine.