How to remove the overlay loader from material table?

You can use OverlayLoading field to remove the overlay loader style of material-table.

<MaterialTable
  columns={columns}
  data={...}
  components={{
    OverlayLoading: props => (<div></div>)
  }}
/>

You can change loadingType to linear in options:

<MaterialTable
  columns={columns}
  data={...}
  options={{
    loadingType: 'linear'
  }}
/>

You can override Overlay loading component like this,

<MaterialTable
  columns={columns}
  data={...}
  components={{
    OverlayLoading: () => <div />
  }}
/>