Firstly IIM Indore does not offer BBA but BA in Foundations of Management. And yes, you can leave IIM Indore after Bachelors. You can then attempt the CAT and apply for top IIMs. In Fact it is a good decision.
I can also provide you with an example. Last year in CAT 2020 an IPM student from IIM INDORE scored 100%ile and then moved to another top IIM. This might motivate you to finalise your decision.