Any low cut, even 0.0005Hz will in theory remove the DC offset entirely - think of it like the rolloff of a filter: e.g. a 12dB per octave filter will remove an additional 12dB for each additional octave (1 octave = doubling of the frequency). That is also true for high pass (= low cut) filters. For each additional octave down (= frequency/2) you’ll get the same amount of suppression.

The DC component has a frequency of exactly zero. How many octaves below e.g. 10Hz is that? Infinitely many octaves, because you can divide 10Hz by 2 infinitely without ever reaching zero. That means that any high pass filter - no matter how steep it’s rolloff is or what the cutoff frequency is - will in eventuell entirely remove the DC component.

There is a catch though: As the cutoff frequency goes lower and lower, it takes more and more time until the DC component is finally completely removed. So if you would apply a 0.001Hz high pass filter to a steady voltage, you’ll see that the filtered signal starts at that voltage and then slowly drops exponentially towards zero. It drops faster the higher you set the cutoff frequency. So in practice you’ll want to choose the high pass frequency as high as possible - just low enough to not remove any wanted frequencies from your signal.

So whatever your DAW offers as the lowest low cut frequency will do the job. If you like, you could “record” a steady voltage in your DAW and apply high pass filters with different frequencies to it and observe the results in the rendered audio.