DC Filter for DC free transmitting
A single capacitor in series removes the DC offset. Done! All you need from your complete schematic is... C3! 

Since "DC offset" is something relative (who gets to decide what "0V" actually is?), you'll then need to bias it around your ground. Something like:







simulate this circuit &ndash; Schematic created using CircuitLab

Upon introspection, we'll find deep in our hearts that this is the well-known structure of an RC high pass filter – which, indeed, removes low frequencies, and especially DC at f = 0Hz. Deal!

The value of the capacitor and resistor define how low your filter will "cut off"; that is, whether lower-frequency sines will still be passed through. (How can you tell the instantaneous value of a sine wave with f = 0.0000001 Hz from a DC offset? You can't, unless you're willing to wait 1000000 seconds.)

Add an opamp voltage follower to the output so that you don't load that filter (and change its properties). 

Thus, even in its fullest configuration, your complete circuit would look something like 







simulate this circuit

which will let through sines down to ca 1/33 Hz, but block DC, with the downside that it'll take about 33s for the thing to reach a perfect DC cancellation. If you can live with blocking sines of higher frequencies, you can make the time constant shorter.