Can someone tell me how to delete 3 months of Chat. Every time I open MIRC it picks up where it left off with a line between chats
By default, there is no feature where you can get mIRC to delete all logs before x days ago from today.
There is a feature, though, where you can set the size of the log files. Suppose you want log files to not exceed 5 megabytes. Since the feature is represented by kilobytes, you'll have to convert. Etc. But no, no date or time reference.