A seller has a right to sell or not to sell and to set the terms.
Russia is stealing Ukrainian grain, destroying crops and equipment and blockading ports, making it impossible for Ukraine to export its grain. So, no - a thief has no right to steal somebody else's grain.
If this is too complicated for you I will try again using different words.
In this case, it's: remove the sanctions or...
...we will steal Ukrainian grain (5th largest world poroducer of wheat alone) and make it impossible for them to sell it, and in this way we'll produce artificially caused famine (we already have a lot of experience in it - see Holodomor). In this way, as many as 1.7 billion people will face hunger and hundreds of millions of them might die of famine. This will make it the greatest mass genocide in the history of planet Earth.
Germans can start celebrating. Nobody in the world will remember about Hitler or Third Reich after Russia conducts this genocide.
And why remove the sanctions at all? They are making Russia stronger - Putin says so...
tass.com/economy/1456363
... so it has to be true, right?