Bear in mind that Excel takes a "Majority Rule" on interpreting data types based solely on the first 8 rows of data. This can cause numerous import type of errors and some to this day Have no work around!
Microsoft SQL Server Integration Services: Mixed data types in Excel column
When working with excel data (killed me to say that) I import the tables into MS Access, clean up the data then bring it into Arcgis from MS Access. However, if you are working with "Pro" your out of luck using this technique (esri chose not to support ms access without purchasing expensive licensing) and you would have to import the data into larger format database to do the same thing (providing you have the security and the ability to create tables from your dbadministrator).