Thank you for the tag!
I am always happy to help
International Relations student here, at your service!
Politics is the most useful A-level one can have for International Relations. I did government and politics and it introduced me to how British politics work and examples that I later used in my essays. Also, it helped me gain the study skills necessary to study international relations at degree level.
Your subjects are already way more diverse than mine were!
I studied government and politics, psychology, sociology, and English literature. International Relations is not a subject for which you definitely need all traditional A-levels and variety.
Your subjects are completely fine, do not worry!
Whether you choose economics or politics depends on your interest in them and your main areas of interest in international relations. Both economics and politics are very good for International Relations (I have had lectures on and used theory from both areas in my university essays), so just pick which one you like most.
I know I just said politics is the most useful A-level for International Relations, but it is far from mandatory. Many (if not most) people who study International Relations or Politics do not have an A-level in government and politics, so do not worry about it, just pick which A-level you would like more and do better in.
Biology is almost useless for International Relations, so I suggest not picking it lest you love it and/or know you will do well in it. French would indeed be very useful in International Relations; a lot of United Nations internships ask for fluency in French (but you can prove fluency with a DELF certificate or university education anyway) and you might be interested in studying it as a module in university, for instance. If you are bilingual, French might be an easy A/A* for you, but the truth is that you do not need an A-level in any language. You do not have to pick it if you do not want to!
If you want, you can always choose to continue your study of French on your own or as an outside module in university. I started to study German as an outside module in university with no GCSE or A-level in a foreign language and I will continue it until I finish university, so I should become at least intermediate in German in a language I had never even considered studying before university.
As for potentially dropping a subject, once again, if you want to have four full A-levels, nothing can stop you, so you do not have to drop anything.
Out of the subjects you mentioned, I believe the least useful one for International Relations in your case is English Literature, but even that is far from useless as the essay-writing and analysis skills you will gain from it is valuable for your future degree.
Just in case you are wondering why I consider Maths to be arguably more useful than English Literature in this case: firstly, you need certain numeracy skills for International Relations. Part of International Relations is research and I struggled to read the more difficult graphs and understand the more mathematical aspects of my course since I only have a C in GCSE maths. Of course, maths is definitely not a must have for International Relations, but it is useful and some universities classify International Relations as a BSc, which means they might put more emphasis on numerical skills. Also, OP, you already have other essay-based subjects like history and politics/economics there, which should prove your essay-writing skills, especially if you choose politics. However, if you pick economics instead of politics, the importance of Maths and English Literature is more or less equal as Economics can prove your numeracy skills too. Either way, whether to drop a subject and which subject to drop is your choice alone, though I would suggest dropping a subject if you do not enjoy or do well in it.
To summarise, politics is more useful and you do not exactly need economics to prove your numeracy skills if you have A-level maths, but you do not need politics either since a lot of International Relations students do not have it as an A-level, so pick which one you think you would like more and do better in. Obviously, I recommend politics as I loved it, but your subjects are fine and I am sure that regardless of which other A-level you choose, you will get an offer.
Feel free to ask if you have any other questions.