Once a Job has been added to the Compensation Tool it automatically is added in each year within the Job Data section, if you have no employees (or override FTE) in the year the job will not be included in the Pay Equity analysis for that year. Hence adding Job data to the wrong year with no employees will not affect your project. However you can remove all the data from any fields you have entered manually within the table by deleting any data entries (ie, highest band or target variable).
If you have entered the wrong Job Title you can edit it within the Job Title Field, please note this will change Job Title for all years.
If you have accidentally uploaded a significant amount of data to the wrong year you can reverse the upload in the Project Management section under the Upload - Save State area, for more information see here.