A fee is a standalone record; for more information about it, see the Fee record.
At the same time, a fee is also a price list item — the Price List record.
The first step is therefore to remove the fee from the price list item:
You need to know the fee ID — first, retrieve the fee ID from the given price list.
<winstrom>
<cenik>
<kod>FEN</kod>
...
<poplatky>
<poplatek>
<id>7</id>
<mnozMj>1.0</mnozMj>
<typPoplatkuK showAs="Obecný">typPoplatku.obecny</typPoplatkuK>
<cenikOtec>code:FEN</cenikOtec>
<cenik>code:RECYKLPOPL</cenik>
</poplatek>
</poplatky>
...
</cenik>
</winstrom>
The fee ID is then used to delete it from the fee record:
<winstrom>
<poplatek action="delete">
<id>7</id>
</poplatek>
</winstrom>
The second step is to delete the standalone fee item from the price list; however, it must not be linked or used anywhere:
<winstrom>
<cenik action="delete">
<id>code:RECYKLPOPL</id>
</cenik>
</winstrom>